From a70cbf7012bcc458422d0d28b5d3c1e440f9abb5 Mon Sep 17 00:00:00 2001
From: Marceli Pawlinski <marceli1404@users.noreply.github.com>
Date: Wed, 2 Sep 2026 00:05:00 +0100
Subject: [PATCH] fix: accept a comma-delimited list in req.acceptsCharsets

---
 lib/request.js              |  4 +++-
 test/req.acceptsCharsets.js | 26 ++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/lib/request.js b/lib/request.js
index 1eb7f9ca16a..a789f60491c 100644
--- a/lib/request.js
+++ b/lib/request.js
@@ -170,7 +170,9 @@ req.acceptsEncodings = function(){
 
 req.acceptsCharsets = function(...charsets) {
   const accept = accepts(this);
-  return accept.charsets(...charsets);
+  return accept.charsets(...charsets.flatMap((charset) =>
+    Array.isArray(charset) ? charset : String(charset).split(',').map((s) => s.trim())
+  ));
 };
 
 /**
diff --git a/test/req.acceptsCharsets.js b/test/req.acceptsCharsets.js
index 2df68ae1097..8116a9943d8 100644
--- a/test/req.acceptsCharsets.js
+++ b/test/req.acceptsCharsets.js
@@ -58,6 +58,32 @@ describe('req', function(){
         .set('Accept-Charset', 'iso-8859-1, utf-8')
         .expect('iso-8859-1', done);
       })
+
+      it('should accept a comma-delimited list of charsets', function (done) {
+        var app = express();
+
+        app.use(function(req, res, next){
+          res.end(req.acceptsCharsets('iso-8859-1, utf-8'));
+        });
+
+        request(app)
+        .get('/')
+        .set('Accept-Charset', 'iso-8859-1, utf-8')
+        .expect('iso-8859-1', done);
+      })
+
+      it('should not modify a single charset when given a comma-delimited list', function (done) {
+        var app = express();
+
+        app.use(function(req, res, next){
+          res.end(req.acceptsCharsets('utf-8, iso-8859-1'));
+        });
+
+        request(app)
+        .get('/')
+        .set('Accept-Charset', 'utf-8, iso-8859-1')
+        .expect('utf-8', done);
+      })
     })
   })
 })