MediumGHSA-9fm3-97px-rjf6CVE-2026-10993215 Oct · 8 days ago
undici WebSocket client vulnerable to Denial of Service via unbounded automatic PONG buffering.
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Conditions read by Claude. The sources remain the reference.GitHub advisory
Timeline
15 Oct8 daysfrom publication to Patchwire
- Published by GitHub advisory15 Oct
- Seen by Patchwire23 Oct
- Fix released15 Oct
undici6.29.17.30.18.12.2
Versions of undici
8.x
safe 8.12.2
7.x
safe 7.30.1
6.x
safe 6.29.1
AffectedSafe
Related alerts(8)
Same packagesExploitable only if · read by Claude, the source remains the reference
- Project uses undici 6.x before 6.29.1, 7.x before 7.30.1, or 8.x before 8.12.2.
- Application calls undici's fetch() against servers that may be attacker-controlled or malicious.
- The server responds with more than five content codings and closes the connection before sending the body.
- Affected
- undici >=6.23.0 <6.29.1 · undici >=7.18.0 <7.30.1 · undici >=8.0.0 <8.12.2
- Fixed in
- 6.29.1 · 7.30.1 · 8.12.2
- ID
- GHSA-xjj6-f33q-929c
Exploitable only if · read by Claude, the source remains the reference
- Project uses undici's EventSource client.
- undici version is below 6.29.1, 7.30.1, or 8.12.2 in the respective major line.
- The application maintains an EventSource connection to an untrusted or potentially compromised Server-Sent Events peer that controls the response.
- Affected
- undici >=6.5.0 <6.29.1 · undici >=7.0.0 <7.30.1 · undici >=8.0.0 <8.12.2
- Fixed in
- 6.29.1 · 7.30.1 · 8.12.2
- ID
- GHSA-4qv8-2p9j-2685
Exploitable only if · read by Claude, the source remains the reference
- Project uses undici at version 7.15.0 or later, below the patched releases 7.30.1 / 8.12.2.
- Application calls undici's fetch() with Subresource Integrity (integrity) metadata.
- The integrity metadata uses an uppercase or mixed-case algorithm token (e.g. SHA256- or Sha256-).
- An attacker can control the response body returned by the server.
- Affected
- undici >=7.15.0 <7.30.1 · undici >=8.0.0 <8.12.2
- Fixed in
- 7.30.1 · 8.12.2
- ID
- GHSA-f72v-6w45-q472
Exploitable only if · read by Claude, the source remains the reference
- undici version is 7.x before 7.30.1 or 8.x before 8.12.2.
- An originless Agent dispatcher is used (not an origin-bound Client or Pool).
- Interceptors are composed as compose(redirect(), cache()) (not compose(cache(), redirect())).
- The cache interceptor uses a shared cache (type: 'shared') backed by a MemoryCacheStore or SqliteCacheStore.
- Requests can follow redirects whose targets can be attacker-controlled or user-specific (e.g. cross-origin or private/no-store redirects).
- Affected
- undici >=7.0.0 <7.30.1 · undici >=8.0.0 <8.12.2
- Fixed in
- 7.30.1 · 8.12.2
- ID
- GHSA-4w7w-5xrc-9h26
Exploitable only if · read by Claude, the source remains the reference
- Project uses undici at a version before 6.29.1, 7.30.1, or 8.12.2.
- Requests are made through undici's Agent (including as default dispatcher for request, fetch, setGlobalDispatcher) or EnvHttpProxyAgent on direct/NO_PROXY routes.
- The Agent is constructed with a function-valued tls option, such as a custom checkServerIdentity callback for certificate or public-key pinning.
- The TLS options are passed via the tls option rather than via connect.
- Affected
- undici >=4.0.0 <6.29.1 · undici >=7.0.0 <7.30.1 · undici >=8.0.0 <8.12.2
- Fixed in
- 6.29.1 · 7.30.1 · 8.12.2
- ID
- GHSA-2m5v-pch6-74hx
Exploitable only if · read by Claude, the source remains the reference
- Project uses undici (directly or via Node.js global fetch()) at a version before 6.29.1, 7.30.1, or 8.12.2.
- The client makes HTTPS requests to an endpoint that is malicious or compromised.
- The connection to that endpoint negotiates TLS 1.2 (not restricted to TLS 1.3).
- The server initiates renegotiation after the connection is established and presents a different CA-trusted certificate whose hostname does not match the requested host.
- Affected
- undici >=4.2.1 <6.29.1 · undici >=7.0.0 <7.30.1 · undici >=8.0.0 <8.12.2
- Fixed in
- 6.29.1 · 7.30.1 · 8.12.2
- ID
- GHSA-qrxm-fqhp-jwvm
Exploitable only if · read by Claude, the source remains the reference
- Project uses undici at a version before 7.30.1 (7.x) or before 8.12.2 (8.x).
- The client composes undici's decompress interceptor with a downstream response handler that throws during response processing (e.g. the dump interceptor with maxSize).
- The client makes requests to an HTTP server that may be malicious or compromised and can return a compressed body that decompresses beyond the configured limit.
- Affected
- undici >=7.15.0 <7.30.1 · undici >=8.0.0 <8.12.2
- Fixed in
- 7.30.1 · 8.12.2
- ID
- GHSA-55wc-3pg8-jfw6
Conditions not read yet
Source summary
Impact undici's experimental WebSocket client (enabled by default via allowH2: true ) crashes the Node.js process when it connects to a malicious server over HTTP/2. If the server answers the WebSocket upgrade with a response that fails handshake validation, undici aborts the request, but the abort is a no-op because the request is already marked completed, so the underlying ClientHttp2Stream is left open with no error listener. When the server then destroys the connection, the orphaned stream emits an unhandled error and the process exits. A remote, unauthenticated server can therefore deny s
- Affected
- undici >=8.11.0 <8.11.2
- Fixed in
- 8.11.2
- ID
- GHSA-qq8j-7v2v-3rwp