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…dersCount A lowered server.maxHeadersCount cut the header list the handler saw, after the parser had framed the message with every field. A Content-Length past the limit was hidden from req.headers and req.rawHeaders and still delimited a body. Node rejects such a request since nodejs/node 821688aaa0 (CVE-2026-58044). The native server now takes the limit as the bound of the field loop in uWS getHeaders, so the existing parse error path answers: 'clientError' with HPE_HEADER_OVERFLOW, 431 by default, no more parsing on the connection. Trailer fields count from zero against the same limit. The value reaches the parser at listen() and on every later assignment. The llhttp binding gets Node's TrackHeaderPair for request parsers, in the revision that reads maxHeaderPairs once per header section (nodejs/node#64988). Responses keep truncating. This covers sockets passed to server.emit('connection') and the HTTP/1.1 connections of an allowHTTP1 HTTP/2 server. That listener now also starts from Node's 2000-pair default and assembles the header blocks and trailers the parser flushes through kOnHeaders. Before, a request with 32 or more fields reached the handler with only its last block, so Host and Content-Length were hidden there too. The JS truncation of rawHeaders and rawTrailers is gone. The vendored Node tests follow upstream: two added, two updated, and test-http-rawheaders-limit.js removed.
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Updated 5:39 PM PT - Sep 12th, 2026
✅ @robobun, your commit 99eadd33e6d206130e1aae2de842d061c9dbf351 passed in 🧪 To try this PR locally: bunx bun-pr 42532That installs a local version of the PR into your bun-42532 --bun |
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Status Closed. #43557 supersedes this PR and is merged (5d5f03f). It carries the same fix and the tests of this PR. Checked on main at 5d5f03f: with |
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I reviewed this PR and didn't find any bugs. Because it changes the loop bound in the hot-path uWS getHeaders parser and threads a CVE-relevant limit across five layers (uWS C++, llhttp binding, Rust FFI, JS builtins), a human look is still worthwhile.
What was reviewed:
getHeadersloop-bound change:maxHeaderFieldsis clamped toMAX_HEADER_FIELDS(198) infenceAndConsumePostPaddedbefore every call, and thestatic_assertbounds it againstHttpRequest::headersextent — no OOB write path.- All call sites updated: both
fenceAndConsumePostPaddedinvocations, all threevalidateNodeTrailerSectionsites, and the soleconsumePostPaddedcaller inHttpContext.h. trackHeaderPair():RETURN_IF_EXCEPTIONafter themaxHeaderPairsproperty read; new counters reset atinit/onMessageBegin/onHeadersComplete/onMessageComplete.- Rust shim and JS accessor mirror the existing
maxHeaderSize/httpAllowHalfOpenpatterns; dead JS truncation removed from_http_incoming.tsandinternal/http.ts.
Extended reasoning...
Overview
This PR ports Node's CVE-2026-58044 fix: server.maxHeadersCount now causes the parser to reject requests (431 / HPE_HEADER_OVERFLOW) instead of silently truncating rawHeaders after the message has already been framed. It touches the uWS HTTP parser (HttpParser.h — loop bound in getHeaders, trailer validation, HttpContextData field, App::setMaxHeadersCount), the llhttp binding (NodeHTTPParser.{cpp,h} — new trackHeaderPair() with per-section maxHeaderPairs caching), Rust FFI plumbing (server_body.rs, mod.rs, uws_sys/App.rs, libuwsockets.cpp), JS builtins (_http_server.ts accessor, http1_server_fallback.ts kOnHeaders assembly, removal of dead truncation in _http_incoming.ts and internal/http.ts), and ~700 lines of tests including vendored upstream Node tests.
Security risks
The change is itself a security hardening. The primary risk to check was whether making the getHeaders field-loop bound runtime-configurable could allow an out-of-bounds write into HttpRequest::headers[200]. It cannot: the only caller (fenceAndConsumePostPadded) computes maxHeaderFields = maxHeadersCount && maxHeadersCount < MAX_HEADER_FIELDS ? maxHeadersCount : MAX_HEADER_FIELDS, so the bound is always ≤ 198, and a static_assert(MAX_HEADER_FIELDS + 2 <= extent_v<...>) pins that against the array size. The old loop ran 198 iterations (i = 1..UWS_HTTP_MAX_HEADERS_COUNT-1); the new default runs the same 198 (i = 0..MAX_HEADER_FIELDS) after the same pre-loop headers++, so the default path is byte-identical. The uint32_t type on maxHeadersCount and the JS-side << 1 int32 arithmetic in nativeMaxHeadersCount mean odd/negative/non-finite user values collapse to 0 (no limit), matching Node.
Level of scrutiny
High. This is a ~960-line change to the request-parsing hot path across C++ (uWS and JSC bindings), Rust FFI, and JS builtins, motivated by a CVE. Per the approval guidelines, changes that are large and touch security-sensitive parsing code should get a human review even when the automated pass finds nothing. The uWS parser in particular is memory-safety-critical and hand-optimized; a maintainer familiar with its invariants should confirm the loop-bound refactor and the three validateNodeTrailerSection call-site updates.
Other factors
Test coverage is thorough: a 555-line test file exercising both the native server and the emit("connection") llhttp path, boundary values around the 31-field flush, trailers, post-listen() assignment, odd maxHeadersCount values, plus four vendored Node parallel tests (two new, two updated to upstream, one deleted with stated reason — it asserted the removed truncation behavior). The new mutable state on HTTPParser (m_headerPairs, m_maxHeaderPairs) is reset at every documented lifecycle point. The Rust Server__setMaxHeadersCount shim is a line-for-line sibling of the existing Server__setMaxHTTPHeaderSize, routed through host_fn::to_js_host_fn_result. The maxHeadersCount accessor in _http_server.ts copies the adjacent defineHttpAllowHalfOpen pattern. No CODEOWNERS entries cover the changed paths. The bug-hunt exit reason was dry_streak.
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…inish, lifecycle) (#43557) One pull request for the open `node:http` server pull requests. Each root cause is fixed once, and each pull request's tests are carried over. Node is the reference: every scenario was run under Node and under Bun from one script, and the outputs were compared. Fixes #4733 Fixes #18613 Fixes #40350 Fixes #43155 Fixes #43297 Fixes #43513 Fixes #43527 Fixes #25632 Fixes #31301 Fixes #43027 Fixes #43163 Fixes #43342 Fixes #43344 Fixes #43370 Fixes #43490 Fixes #43512 Fixes #43519 Each of these has a repro that is wrong on Bun 1.4.3, right on this branch, and the same as Node. | Issue | Not closed by this PR, because | | --- | --- | | #30501 (msal-node keeps Bun alive at exit) | Probably fixed. The repro copies the teardown of msal-node. The package itself was not run. | | #14430 (yarn: "does not support SSL") | Probably fixed. `response.hasOwnProperty("socket")` is now `true`. yarn itself was not run. | | #39681 (`server.setTimeout` callback after destroy) | Probably fixed. The repro is the deterministic case of #39686. The script in the issue depends on timing and on Windows. | | #43455 (`req.complete`, nine flows) | Partially addressed. Flows 1, 2, 3, 5 and 7 are fixed, and flow 6 was already right. Flow 8 (a socket timeout while the body of an Upgrade request arrives) and flow 9 (a request that `stream.pipeline()` destroyed never reports `complete`) are not. Flow 4 differs only in `_readableState.ended`. | ### What changes for users | Area | Before | After (same as Node) | | --- | --- | --- | | `req.pause()` | The socket stops at once. `req.complete` stays `false` for a small body. | The body is received until the buffer is full. Then the socket stops. | | `res.end()` before the body arrives | `req` gets `'end'` and `'close'` at once, and the body is lost | The request completes when its body really ends | | `res.destroy()` in the middle of a body | `'end'` with bytes missing | `aborted`, then `ECONNRESET` | | `socket.destroy()` inside the `'request'` listener | The body that came with the head is dropped | That body is still delivered | | `'finish'` and the `end()` callback | Fire when `end()` buffers the bytes | Fire when the last bytes have left the socket | | A response that closes the connection | The server half-closes and waits for the peer | The socket closes right behind the FIN | | `'drain'` after a later write flushed the backlog | Lost. `pipe(res)` could hang. | Emitted | | A pipelined request whose body continues after the previous response ends | Body dropped, no response, `server.close()` hangs | Delivered | | CONNECT and Upgrade tunnel sockets | Keep reading when paused or full | Stop reading. `_read()` starts them again. | | A tunnel write that waits for a drain when the client goes away | Its callback, the callbacks of the writes behind it and the `end()` callback never run | They run with an error before `'close'` | | Upgrade request with a body, paused in its listener | The body flows away | The request keeps its body | | `ws` on a reused keep-alive socket | Writes after the Upgrade could stall | Sent | | A raw `socket.write()` behind a response that still drains (the 400 for a bad pipelined request, the reply of a `'clientError'` listener) | Lands in the middle of that response | Sent after it | | `server.close()` | Could report closed while connections were open | Waits for every connection. An idle tunnel does not keep the process alive. | | `closeAllConnections()` on a listening server | Also stops the listener and destroys tunnels and WebSockets | Destroys only the HTTP connections | | `Proxy-Connection: close` (node:http only) | Ignored. The connection stays open. | Ends the connection, like `Connection: close` | | A response larger than 16 KB, also in `Bun.serve` and over TLS | Up to 4 `send()` calls for each chunk. Slower than Node in most cases. | One write for the writes of one tick. 1.1x to 2.7x the requests per second of main, and faster than Node. | | `socket.destroy()` and then `res.end()` in a listener | (this PR, earlier) `req` ended as if it were complete | `'aborted'`, then `ECONNRESET` | | `emit('connection')` or http2 `allowHTTP1`: the response ends while the listener still reads the body | The rest of the body is dropped | The body is complete | | `httpValidation: "relaxed"`, `Content-Length` or `Transfer-Encoding` in trailers | Accepted | `HPE_INVALID_CONTENT_LENGTH`, `HPE_INVALID_TRANSFER_ENCODING` | | `req.complete` inside `'connect'`, and inside `'upgrade'` without a body | `false` | `true` | | `optimizeEmptyRequests`: `socket.parser.incoming` after the response | Keeps the request alive on an idle connection | `null` | | A HEAD or OPTIONS request with `Content-Length` | The body is dropped, and `req.complete` is `true` before it comes | The request has its body | | `res.end(chunk)` after the client went away | `finished` and `writableEnded` stay `false`, no `'prefinish'` | The response ends | | An HTTP/1.0 request with an `Expect` header | `100 Continue`, `'checkContinue'`, `'checkExpectation'` or a 417 | A plain `'request'` | | The idle sweep of `close()` and `closeIdleConnections()` | Could destroy a connection that was still receiving a request, or whose response was still draining | Closes only idle connections | ### Design | Piece | What it is | | --- | --- | | Request body state | `None / Pending / Complete / Aborted / Upgraded / Detached`. Only the last chunk sets `Complete`. One function, `leave_pending`, is the only other way out of `Pending`. | | Read flow control | One path: `push()` returning false stops the socket, `_read()` starts it. Both native pause buffers are removed: no read is copied and replayed. | | "This read is parsed" signal | `notifyWhenReadParsed()` sets a uws state bit. uws delivers a `readParsed` event after the read. It replaces a `setImmediate`. | | Close during a parse | One uws bit defers a close to the end of the current message. | | Response finish | A response is finished when it has ended and the socket has fully drained. | | Idle connection | One rule, `HttpResponse::closeIfIdle()`. A connection is idle when it receives no request (head or body) and no response is in flight, queued or undrained. The sweep of `close()` and `closeIdleConnections()` both use it. | | Idle tunnel | A tunnel at read EOF with nothing left to send. uws reports it to the server through the connection filter (`-3`, `+3`, `-4`). It still counts for `'close'`, but it does not hold the event loop, like a libuv handle in that state. | | Server `'close'` | One native close promise per `listen()`. `close()` records whether its sweep left nothing open. Then a `listen()` in the same tick cannot hold `'close'` back, as in `net.Server._emitCloseIfDrained`. | | Raw socket writes | While uws holds response bytes (its buffer, the zero-copy tail of a `res.write()`, the cork buffer), a raw write goes through `AsyncSocket::write`, the path a 1xx line takes. So the order on the wire is the order of the calls. | | Upgrade verdict | One scanner and one verdict, shared by the parser and the dispatcher. | | llhttp | Updated from 9.3.0 to 9.4.2, as Node v26.5.0 vendors it, plus one local patch (see below). Node v26.5.1 and later vendor 9.4.3. That update is not in this PR. | The parser changes also tighten request framing so that it agrees with llhttp in more cases. There is no new API surface. ### A pause holds from the next read The copy of the rest of a read (`nodeHttpPausedSpill`), its replay from a posted task and the nested parse are removed. Like in Node, the rest of the read that caused a pause is still parsed, and the socket stops at the next read. usockets reads up to 512 KB in one call. libuv reads 64 KB. | One paused, unread request (client sends 64 MB) | Bytes held | | --- | --- | | Node 25.6 | 131,018 | | This pull request | 524,234 | The price is in one case. A client sends 512 KB of small pipelined requests (19,418 of them) and never reads. Each handler answers with its own 64 KB body: | Handler | Runtime | Requests dispatched | RSS | | --- | --- | --- | --- | | Answers at once | Node 26.3 | 2,425 | +177 MB | | Answers at once | main | 41 | +9 MB | | Answers at once | This PR | 2,425 | +171 MB | | Answers one tick later | Node 26.3 | 4,850 | +336 MB | | Answers one tick later | main | 2,426 | +181 MB | | Answers one tick later | This PR | 4,850 | +330 MB | Release builds on Linux x64. This PR now does what Node does. main held fewer responses, mostly for a handler that answers at once. On macOS one read can return all 512 KB. There, Bun 1.4.3 already reached +951 MB for the handler that answers one tick later, and Node reached +1,294 MB. `server.maxRequestsPerSocket` bounds it. ### Performance #### Responses larger than 16 KB are faster, and now faster than Node On main, a response that did not fit the 16 KB uWS cork buffer released the cork. After that, each piece was its own `send()`: the buffered head, the chunk-size line, the data, the `\r\n` and the last chunk. Over TLS, each 2-byte piece was also its own record. Two changes fix that, for `Bun.serve` and for node:http: | Change | Effect | | --- | --- | | A write that does not fit goes out with the cork buffer and its framing in one vectored write | No copy is added. Over TLS, the records of all the pieces share the write batch that one `SSL_write` loop already had. | | The cork buffer holds 128 KB, up from 16 KB. Only a write of 16 KB or less is copied into it, as before. | Several writes in one tick go out in one write, like in Node. A longer write still goes out without a copy. | The bytes on the wire are the same. The vectored write uses `sendmsg()` with the flags that `send()` uses. Write syscalls for one response: | Response | Node 26.3 | main | This PR | | --- | --- | --- | --- | | 4 x `res.write(16 KB)` | 1 | 16 | 1 | | 40 x `res.write(2 KB)` | 1 | 16 | 1 | | `res.end(64 KB)` | 1 | 2 | 1 | | 256 KB file, `.pipe(res)` | 4 | 16 | 5 | Throughput (req/s, the mean of 2 rounds). Node v26.3.0, main `97246d044e`, this PR `fe0ed1fbea`, with the method below: | Case | Node | main | This PR | main / Node | PR / Node | PR / main | | --- | --- | --- | --- | --- | --- | --- | | http, 4 x `res.write(16 KB)` | 17,735 | 6,983 | 19,160 | 0.39x | 1.08x | 2.74x | | https, 4 x `res.write(16 KB)` | 11,720 | 6,110 | 15,510 | 0.52x | 1.32x | 2.54x | | http, 40 x `res.write(2 KB)` | 9,879 | 6,140 | 14,980 | 0.62x | 1.52x | 2.44x | | https, 40 x `res.write(2 KB)` | 6,981 | 5,541 | 11,780 | 0.79x | 1.69x | 2.13x | | http, `res.end(64 KB)` | 18,535 | 16,528 | 19,889 | 0.89x | 1.07x | 1.20x | | http, 256 KB file `.pipe(res)` | 2,684 | 2,375 | 2,719 | 0.88x | 1.01x | 1.15x | | https, `res.end(64 KB)` | 11,894 | 14,586 | 16,426 | 1.23x | 1.38x | 1.13x | | http, GET hello (control) | 55,994 | 70,989 | 71,958 | 1.27x | 1.29x | 1.01x | main was slower than Node in six of these eight cases. This PR is faster than Node in all eight. `Bun.serve`, measured on `a771572a8d`, before the larger cork buffer (req/s, the mean of 2 rounds): | Case | main | PR | Change | | --- | --- | --- | --- | | Direct stream, 4 x 16 KB | 6,826 | 12,479 | +83% | | 64 KB string | 16,944 | 20,145 | +19% | | TLS, 64 KB string | 15,045 | 16,892 | +12% | | hello (control) | 83,957 | 83,137 | -1.0% | These runs are on loopback, where the kernel send buffer is 2.6 MB and the work of the receiver runs inside `send()`. That is the best case for fewer writes. A new connection over a real network takes about 46 KB in its first write on Linux. The rest waits in the socket buffer, as it would after separate writes. #### Small responses are unchanged A small response is already one `recvfrom` and one `sendto` on both builds. `perf` puts 66% of the time of a hello-world server in the kernel, on both builds. CI release builds on Linux x64: main `97246d044e` (the merge base) against this PR `8834cd0787`. Both use the same WebKit. The server runs on one pinned core. `oha` sends 64 connections for 5 s after a 2 s warm-up. There are 2 rounds, and the order of the builds alternates. "Change" compares the means of the two rounds. Framework servers from `bun-perf-tester` (req/s): | Server | main, round 1 | main, round 2 | PR, round 1 | PR, round 2 | Change | | --- | --- | --- | --- | --- | --- | | express | 49,803 | 51,103 | 49,968 | 50,263 | -0.7% | | fastify | 61,214 | 61,105 | 60,705 | 60,668 | -0.8% | | node:http | 70,934 | 71,405 | 73,178 | 71,053 | +1.3% | | elysia | 84,696 | 85,096 | 85,027 | 84,882 | +0.1% | | `Bun.serve` | 89,020 | 89,099 | 88,168 | 88,373 | -0.9% | node:http paths that this PR changes (req/s): | Case | main, round 1 | main, round 2 | PR, round 1 | PR, round 2 | Change | | --- | --- | --- | --- | --- | --- | | GET hello | 70,226 | 70,341 | 70,151 | 72,359 | +1.4% | | POST, 16 KB body | 47,446 | 47,789 | 48,191 | 48,785 | +1.8% | | 64 KB response in four writes | 6,885 | 6,894 | 6,834 | 6,868 | -0.6% | | Pipelined keep-alive, depth 8 | 94,063 | 93,294 | 92,909 | 93,809 | -0.3% | p99 latency (ms), the higher of the two rounds: | Server | main | PR | | --- | --- | --- | | express | 1.94 | 1.91 | | fastify | 1.52 | 1.55 | | node:http | 1.11 | 1.12 | | elysia | 0.98 | 0.96 | | `Bun.serve` | 0.82 | 0.83 | RSS (MB), one pass of 8 s of load: | Server | Build | Start | Under load | 5 s idle | 15 s idle | | --- | --- | --- | --- | --- | --- | | express | main | 39 | 94 | 61 | 57 | | express | PR | 40 | 92 | 60 | 57 | | fastify | main | 41 | 91 | 58 | 55 | | fastify | PR | 41 | 91 | 58 | 55 | | node:http | main | 20 | 64 | 43 | 40 | | node:http | PR | 20 | 65 | 45 | 41 | | elysia | main | 28 | 46 | 36 | 35 | | elysia | PR | 29 | 46 | 37 | 36 | | `Bun.serve` | main | 14 | 30 | 22 | 22 | | `Bun.serve` | PR | 14 | 30 | 22 | 22 | Every change is within 2%. fastify and `Bun.serve` hello are lower in both rounds, by about 1%. `Bun.serve` hello shows the same -1.0% in the control row above, so a small real cost there is possible. The RSS pass ran at the same time as the throughput runs, on other cores. The commits after `8834cd0787` change tests and add one version check to the node:http dispatcher. They were not measured. ### Supersedes | Theme | Pull requests | | --- | --- | | Request body | #43592 #43579 #38196 #43518 #43602 #43408 #43427 #43597 #43555 #43456 #43466 | | Tunnels | #43570 #43485. #43596 is a duplicate of #43570. | | Parser | #43182 #43161 #43326 #43327 #40505 #43363 #42532 #42194 | | Response write | #39386 #43371 #43548 #43499 #43496 #43464 #42008 #43549 | | Response finish | #40351 #43021 #41822 #43473 #42068 #35207 #43425 #43503 | | Lifecycle | #43413 #39686 #43028 #42727 #42622 #42610 #35837 #35839 #37825 #37749 #43376 #35268 | | JS API | #41691 #41738 #38036 #42462 #36527 #39718 #37964. #42947 merged on its own. | The close drain, `resetAndDestroy()`, the pending write callback handling and the response `'close'` ordering come from #42622 and #42727 by @steipete. The diagnosis and the tests for the stalled `ws` writes come from his #42610. Not included: | Pull request | Reason | | --- | --- | | #33061 | main already enforces `headersTimeout` and `requestTimeout` | | #41672 | It makes `http.createServer({ key, cert })` stop serving TLS. That needs a product decision. | | #37543 | A type refactor with no tests and no user-visible change | | #35465 | It makes `http.Server` extend `net.Server`. Only the prototype chains were joined. The `net.Server` constructor never ran, so `_handle` and `_connections` were `undefined`, and `_emitCloseIfDrained()` emitted `'close'` on a listening server. The server is backed by uWS, not `node:net`. | | The `AutoFlusher` removal in #42622 | It makes `flushHeaders()` flush at once. That is a performance change with no relation to the rest. | ### Tests | Check | Result on a debug build (macOS arm64) | Head | | --- | --- | --- | | Every test file that this PR touches (28 files) | 1,866 pass, 2 fail. The 2 failures are `serve.test.ts` "bounds memory when proxying ... to a stalled client". They fail the same way on a debug build of main. | `83af4da4a3`, run before the last commit of main came in | | `test/js/third_party/express` (9 files) and the `body-parser` test | 299 pass, 0 fail | `83af4da4a3`, run before the last commit of main came in | | Node 25.6 against Bun, 32 scenarios from two scripts (event order, framing, lifecycle) | No regression against Bun 1.4.3 | `0ff1a23f61` | | Every vendored Node `test-http-*` and `test-https-*` file, plus the `test-net-*` and `test-tls-*` files for pause, write, end and close | 535 of 537 exit 0. `test-http-agent-keepalive.js` and `test-https-timeout.js` fail on that debug build. Both pass on every CI lane. | `daee05fcfd` (before the rebase) | | The tests that depend on what the kernel takes in one send, on Windows Server 2019 x64 and Windows 11 arm64 | pass | `3eef223328` (x64), `a29289bcc1` (arm64) | | CI build 120191 (Linux, macOS and Windows, release and ASAN) | every lane passed | `daee05fcfd` (before the rebase) | Each new test fails on Bun 1.4.3, or on the commit before its fix for a fault that this branch introduced. The two tests over the limit are `node-http-connect.test.ts` ("tests should run on bun") and `node-http-syscall-fault.test.ts` ("racing a queued drain"). Each starts a debug subprocess that needs more than 5 s on this machine. Both pass on CI. ### Changes in the last push The branch is rebased on main (`daee05fcfd` was the head before). It is now linear. Four regressions against main, each with a test that fails without its fix: | Case | main | Before this push | Now (same as Node) | | --- | --- | --- | --- | | `emit('connection')` or http2 `allowHTTP1`: `res.end()` on a request that nobody reads | `'end'`, `'close'` | No events | `'end'`, `'close'` | | The same server, an unread 32 MB body | 0 bytes held | 32 MB held | 0 bytes held | | A NUL in a header value with `httpValidation: "relaxed"` (client, `HTTPParser`, `emit('connection')` server) | Accepted | The process spins forever | `HPE_INVALID_HEADER_TOKEN` | | `Connection: close`, body in the same read as the head, a 20 KB response before the body is read | `'end'` with an empty body | No events on `req` | `'end'` with the body, `'close'` | | An empty line on an idle keep-alive connection, then `server.close()` | 0 s | About 6 s | 0 s | | Fix | Where | | --- | --- | | The finish listener of a fallback connection dumps an unread request, like Node's `resOnFinish` | `http1_server_fallback.ts` | | llhttp patch: `llhttp__internal__c_test_lenient_flags_20` is false for a NUL. The relaxed state does not consume a NUL, and the next state sent it back there. 9.4.3 has the same loop. | `llhttp.c`, noted in its `README.md` | | A node:http socket that `onData` is parsing gets the close gate of `onData`, also when a large write released the cork | `HttpResponse.h` `uncorkCompletedResponse()` | | A read that starts no message leaves an idle connection idle | `HttpContext.h` `onData` | The open review threads are fixed in `8834cd0787`: `closeAllConnections()`, `Proxy-Connection: close`, five comments cut to one line, and the test of two overlapping listeners, which now waits on events. With the generation gate in `emitCloseServer` removed, that test fails in both cases. `AsyncSocketData` keeps its bools together, which takes it from 56 to 48 bytes per socket. `http.Server` no longer extends `net.Server` (see "Not included"). The special case for it in `Ipc.ts` is gone too. `child.send(msg, httpServer)` still throws `ERR_INVALID_HANDLE_TYPE`, and its test stays. <details><summary>Changes since the first revision (2988a61)</summary> Merged with main at `c8e1f6fa5b`. The one conflict was #43708 (`req.socket` emits `'end'` and `'error'`). Its state bit `HTTP_NODE_PEER_ENDED` moved to bit 22, because bit 19 is `HTTP_NODE_NOTIFY_READ_PARSED` here. Its 15 tests run in `node-http-server-abort-events.test.ts` next to the tests of this branch (103 pass). CI on `2988a610c` had ten red tests from four causes. They are fixed: - `ed882e5e99`: `write()` to a response without a body (HEAD, 204) does not wait for unsent bytes. - `811f817704`: an idle tunnel does not hold the event loop after `server.close()`. Four vendored Node tests timed out on every platform. - `0697deec11`, `d428824c08`, `7aec062d14`: the write callback tests use a body that backs up a loopback socket, and accept what Winsock does. - `c7af1c1615`: two tests from main asserted the old `close()` contract. Review findings, each reproduced against Node v26.3.0 and fixed with a test that fails without the fix: - `d4d2b783ea`, `2cc79939bb`, `45141abca9`, `9a63dbc470`, `80a23a1822`: the idle rule. A keep-alive connection is idle again when its body ends after its response. A connection that owes a queued pipelined response, that still receives a request head or body, or whose response still drains is not idle. - `87d8904aa3`, `7eca4f7806`: `close(cb)` followed by `listen()` in the same tick reports `'close'`, also for an https server whose only connection was idle. - `3fd7b25382`: a paused pipelined request behind a response that still drains stops the connection. The first revision read 512 MiB of 512 MiB into memory. - `2d1a5e2d8d`, `33e4683a8a`, `539cb41eb9`, `197c7dfc29`, `0490e3540b`: raw socket writes stay behind every unsent response byte. The cases were a CONNECT pipelined behind a response that still drains (its `200` landed at offset 2.6 MB of a 64 MiB body), a zero-length tunnel write (it hung the tunnel), the 400 replies above, the zero-copy tail of a large `res.write()`, the cork buffer, and Windows 11, where the kernel takes the whole response and refuses the next send. - `0abd39c133`: an upgrade from the request's `'end'` listener keeps the body bytes out of the WebSocket. The connection closed with 1006 right after the 101. - `5aafc61aa6`: the callback of a small `res.write()` that the kernel refuses at the uncork runs on the drain. Reproduced on Windows 11 only. - `a29289bcc1`: a tunnel write that waits for a drain settles its callbacks when the connection closes. Known differences from Node that this PR leaves: - A handler that calls `res.end()` and then `server.close()` closes its keep-alive connection at once. Node waits for the `keepAliveTimeout`. - A pipelined Upgrade behind a response that still drains is served as a plain request. - An `end()` on a tunnel with no write pending, while the response before the CONNECT still drains, closes both directions after the flush. Node half-closes. - A raw `req.socket.write(big)` and `req.socket.end()` with no `res.end()` sends every byte but no FIN. main loses bytes here. - A CONNECT socket that is given back with `server.emit('connection', socket)` answers only the first of several pipelined requests. main answers none. - A large write from an `'upgrade'` listener stalls while the body of that Upgrade request is still pending. A second `listen()` on a listening server does not throw. Both are the same on main. - A tunnel write that fails because the client went away fails its callbacks but emits no `'error'`. Node emits `ECONNRESET`. A new `'error'` could end a process that has no listener for it. </details> <!-- robobun:evidence:begin --> --- **no test proof** · iteration 8 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/js/web/fetch/fetch.stream.test.ts, test/js/node/url/url.test.ts, test/js/node/tls/tls-syscall-fault.test.ts, test/js/node/net/node-net-server.test.ts, test/js/node/http/node-http.test.ts, test/js/node/http/node-http-syscall-fault.test.ts, test/js/node/http/node-http-server-close-drain.test.ts, test/js/node/http/node-http-connect.test.ts, test/js/node/http/node-http-backpressure.test.ts, test/js/node/child_process/child_process_ipc_handle.test.ts, test/js/bun/http/serve.test.ts, test/js/bun/http/serve-syscall-fault.test.ts, test/js/bun/http/bun-server.test.ts <!-- robobun:evidence:end --> --------- Co-authored-by: Jarred Sumner <jarred@jarredsumner.com> Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
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Problem
server.maxHeadersCounthid header fields from the handler, not from the parser. AContent-Lengthpast the limit leftreq.headersandreq.rawHeaders, and still framed a body. Node fixed this as CVE-2026-58044 (nodejs/node@821688aaa0): the parser rejects the request with431andclientErrorHPE_HEADER_OVERFLOW.rawHeadersgetter (src/js/node/_http_incoming.ts:221) sliced the list after the native parser framed the message. That copied Node before its fix, and its author invited a change.Fix
getHeaderstakes the limit as its field loop bound, clamped to the 198 fields the array holds. One more field takes the existing parse error path. Trailers count against the same limit. The value reaches uWS atlisten()and on each assignment.TrackHeaderPair, request parsers only. The fallback listener starts from Node's 2000-pair default and assembles the blocks the parser flushes throughkOnHeaders. Before, 32 or more fields reached the handler as the last block only.431.test/js/node/http/node-http-maxHeadersCount.test.ts(67 of 67 on Node v26.5.1, 42 fail on bun 1.4.3). Self-reviewed: 14 concerns, 13 addressed, 1 declined.Background
http.Serverconnections.HttpRequest::headershas 200 slots: the request line, 198 fields, an end sentinel.HTTPParser(llhttp) parsesserver.emit("connection", socket)sockets andallowHTTP1HTTP/2 servers. It hands fields past the 31st tokOnHeaders.socketOnErroras Node's error.Notes
Reproduction.
POST /a {"host":"x","a":"1","b":"2"} rawHeaders pairs = 3 body bytes = 28, thenHTTP/1.1 200 OKclientError HPE_HEADER_OVERFLOW, thenHTTP/1.1 431 Request Header Fields Too LargeclientError HPE_HEADER_OVERFLOW, thenHTTP/1.1 431 Request Header Fields Too LargeWith no
clientErrorlistener both Node v26.5.1 and this branch write exactlyHTTP/1.1 431 Request Header Fields Too Large\r\nConnection: close\r\n\r\n.Matrix against Node v26.5.1. A probe of 13 scenarios on the native server and 10 on
emit("connection")prints the same result on Node v26.5.1 and on this branch: at the limit, one over,clientError,maxHeadersCount = 0, more than 32 fields, trailers at and over the limit, assignment afterlisten(), a client response overreq.maxHeadersCount, odd values (2.5allows 2 fields, and0.5,-1,NaN,Infinity,"3"set no limit), 1000 and 1001 fields with the option unset. Two results differ, and both predate this change:err.reasonis unset anderr.bytesParsedis the packet length on every parse error of the native server, and bun answers a pipelined request before it parses the next one, so a first response can precede the431.Node versions. The reject shipped in v22.23.2, v24.18.1 and v26.5.1. The per-section cache of
maxHeaderPairs(nodejs/node#64988) shipped in v24.21.0 and v26.8.0, andtrackHeaderPairports that revision. In the test file the reject cases skip on an older Node, with the reason. Node v26.3.0 runs 40 and skips 27. Node v26.5.1 runs 67. This branch runs those 67 plus one case that runs the file under Node.Scope.
ClientRequest.maxHeadersCount, as in every Node release. http: reject responses exceeding header limit nodejs/node#65010 (open, semver-major) proposes to reject them too.test-http-max-headers-count-overflow.js(new),test-http(s)-max-headers-count.js(updated) and the removal oftest-http-rawheaders-limit.jsare upstream commit 821688aaa0, byte for byte.test-http-parser-max-header-pairs-cache.jsis from v26.8.0. The removed test asserts the truncation and cannot complete after the fix, on Node or here.test/expected-durations.jsonis generated and is not edited.server.maxHeadersCountis now an accessor on the server, likehttpAllowHalfOpen, so that an assignment afterlisten()reaches uWS. Express users set it on the server thatapp.listen()returns, so this path matters. The limit lives on the server's uWS context, not on the connection: a lowered value applies to open keep-alive connections at once, where Node applies it to connections accepted later. A general way to sync server options afterlisten()would replace the accessor. For exampleserver.maxHeaderSizeassigned afterlisten()is still ignored, before and after this PR.err.codethan Node. The connection fails in both cases.Sibling PRs (all robobun, none reviewed).
requireHostHeaderpart. It has to drop itsMath.minclamp and change its twomaxHeadersCount = 3cases to431.Server__setMaxHeadersCount,HttpContextData::maxHeadersCount,uws_app_set_max_headers_count). Its body says truncation below the built-in limit matches Node, which is no longer true.Self-review. Addressed: port the upstream revision of
TrackHeaderPairthat is current, and vendor its test. Seed the 2000-pair default. Assemble flushed header blocks and trailers in the fallback, and assert field counts there. List the sibling PRs explicitly. State the scope. Declined: a split by parser backend.REVIEW.mdcounts fast and slow parser paths as one concern, and the llhttp half is what keeps the fallback from a silent truncation.Fixed in passing.
maxHeadersCount = 0.5truncatedreq.rawHeadersto half a pair. Node reads it as no limit (0.5 << 1is 0), and so does this branch.Cost. Default path of the native server: one
uint32_tread and one comparison per parse call, no branch per field.HttpContextDatagrows by oneuint32_t. Request parsers of the llhttp binding read one property per header section.Suites run on the debug and ASAN build.
node-http-maxHeadersCount.test.ts(68 pass),node-http.test.ts(159 pass, 1 skip),node-http2.test.js(387 pass, 6 skip),node-http-parser,node-http-transfer-encoding,node-http-maxHeaderSize,node-http-primoridals,node-http-server-timeouts, and 190 vendoredtest-http*,test-https*andtest-http2-*fallback*files that touch headers, trailers, the parser, pipelining orclientError. 188 pass.test-http-agent-keepalive.jsandtest-https-proxy-request-incomplete-headers.mjsfail in this container with and without this diff.BUN_JSC_validateExceptionChecks=1is clean on the parser cases.[human-review] gate passed · iteration 0 · 23 files touched
fails on main (without fix)
passes on PR (with fix)
diff hotspot
gate history · 1 passed · 0 rejected · iteration 0
evidence per changed file