diff --git a/dstack/gateway/src/kv/mod.rs b/dstack/gateway/src/kv/mod.rs
index 07dfcf228..7315bc1a6 100644
--- a/dstack/gateway/src/kv/mod.rs
+++ b/dstack/gateway/src/kv/mod.rs
@@ -682,6 +682,8 @@ impl KvStore {
     /// This stores the URL in KvStore (for address lookup) and also adds the node
     /// to the wavekv peer list (so SyncManager knows to sync with it).
     pub fn register_peer_url(&self, node_id: NodeId, url: &str) -> Result<()> {
+        validate_peer_url(url)?;
+
         // Store URL in persistent KvStore
         self.persistent
             .write()
@@ -1033,3 +1035,39 @@ impl KvStore {
         self.persistent.watch_prefix(keys::CERT_PREFIX)
     }
 }
+
+fn validate_peer_url(url: &str) -> Result<()> {
+    let parsed = reqwest::Url::parse(url).context("invalid peer URL")?;
+    anyhow::ensure!(
+        matches!(parsed.scheme(), "http" | "https"),
+        "peer URL scheme must be http or https"
+    );
+    anyhow::ensure!(parsed.host_str().is_some(), "peer URL must include a host");
+    anyhow::ensure!(
+        parsed.username().is_empty() && parsed.password().is_none(),
+        "peer URL must not contain credentials"
+    );
+    Ok(())
+}
+
+#[cfg(test)]
+mod peer_url_tests {
+    use super::validate_peer_url;
+
+    #[test]
+    fn accepts_http_sync_urls() {
+        assert!(validate_peer_url("https://gateway.example:8011/sync").is_ok());
+        assert!(validate_peer_url("http://127.0.0.1:8011").is_ok());
+    }
+
+    #[test]
+    fn rejects_malformed_or_unsafe_sync_urls() {
+        for url in [
+            "not-a-sync-url",
+            "ftp://gateway.example/sync",
+            "https://user:secret@gateway.example/sync",
+        ] {
+            assert!(validate_peer_url(url).is_err(), "accepted {url}");
+        }
+    }
+}