What's Changed

• ci: use Python 3.14 for the WPT server on macOS by @mrityunjay-pandey in #6029
• build(deps-dev): bump neostandard from 0.13.0 to 0.14.0 by @dependabot[bot] in #6006
• build(deps-dev): bump eslint from 9.39.4 to 10.12.0 by @dependabot[bot] in #5967
• docs: document the options of interceptors.cache() by @qodelicious in #6050
• fix(h2): replace a connection that stops responding after a stream timeout by @mcollina in #6052
• fix(pool): keep caller async context for queued requests by @mcollina in #5982

New Contributors

• @qodelicious made their first contribution in #6050

Full Changelog: v8.12.2...v8.12.3

Security fixes

High severity

Denial of service via TLS 1.2 certificate-changing renegotiation

CVE-2026-87018 · GHSA-qrxm-fqhp-jwvm

A malicious or compromised HTTPS server could crash the Node.js process by initiating TLS 1.2 renegotiation and presenting a different, CA-trusted certificate whose hostname did not match the requested host. The resulting socket error reached an assertion in undici's HTTP/1.1 and HTTP/2 connection handling. This release handles post-connect certificate errors without terminating the process.

TLS certificate validation bypass through dropped Agent options

CVE-2026-109383 · GHSA-2m5v-pch6-74hx

Agent used a JSON-based clone for constructor options, which silently removed function-valued TLS options such as checkServerIdentity. Applications relying on custom certificate or public-key verification could therefore accept a certificate that the callback was intended to reject. This release preserves TLS options when creating per-origin dispatchers.

Cache poisoning and cross-user disclosure through cross-origin redirects

CVE-2026-109829 · GHSA-4w7w-5xrc-9h26

When an originless Agent combined redirect and shared-cache interceptors as compose(redirect(), cache()), a response from a cross-origin redirect could be stored under the original URL. This could allow persistent cache poisoning or disclosure of user-specific responses to later callers. This release verifies the response origin before caching and preserves redirect-hop cache-control policy.

Denial of service through excessive Content-Encoding values

CVE-2026-109869 · GHSA-xjj6-f33q-929c

A malicious HTTP server could crash the Node.js process by returning more than five content codings and closing the connection before sending the body. Although fetch() rejected the response, an error from an orphaned internal stream could remain unhandled. This release validates the content-encoding chain before creating the body stream and aborts oversized chains safely.

Medium severity

Denial of service through the decompress interceptor

CVE-2026-87029 · GHSA-55wc-3pg8-jfw6

An exception thrown by a downstream response handler from an asynchronous decompression callback could escape as an uncaught exception. A server could trigger this when decompress was composed with a handler such as dump with a size limit. This release converts downstream handler exceptions into per-request errors.

Subresource Integrity bypass with non-lowercase algorithm tokens

CVE-2026-109841 · GHSA-f72v-6w45-q472

fetch() treated valid mixed-case or uppercase SRI algorithm tokens, such as SHA256, as unknown and could accept a response whose body did not match the configured digest. This release normalizes algorithm tokens before validation and digest selection.

Denial of service through unbounded EventSource parser state

CVE-2026-109924 · GHSA-4qv8-2p9j-2685

A malicious Server-Sent Events endpoint could exhaust process memory by sending many tiny data: fields without completing an event, or by splitting an unfinished line across many chunks. This release bounds retained EventSource parser state, including field counts, buffered chunks, unfinished-line length, and retained field data.

Denial of service through unbounded automatic WebSocket PONG buffering

CVE-2026-109932 · GHSA-9fm3-97px-rjf6

A malicious WebSocket server could exhaust process memory by flooding the client with PING frames while not reading the automatic PONG responses. undici previously ignored socket backpressure and allowed the outbound queue to grow without bound. This release pauses frame parsing when PONG writes encounter backpressure and resumes after the socket drains.

Full Changelog: v8.12.1...v8.12.2

Security fixes

High severity

Denial of service via TLS 1.2 certificate-changing renegotiation

CVE-2026-87018 · GHSA-qrxm-fqhp-jwvm

A malicious or compromised HTTPS server could crash the Node.js process by initiating TLS 1.2 renegotiation and presenting a different, CA-trusted certificate whose hostname did not match the requested host. The resulting socket error reached an assertion in undici's HTTP/1.1 and HTTP/2 connection handling. This release handles post-connect certificate errors without terminating the process.

TLS certificate validation bypass through dropped Agent options

CVE-2026-109383 · GHSA-2m5v-pch6-74hx

Agent used a JSON-based clone for constructor options, which silently removed function-valued TLS options such as checkServerIdentity. Applications relying on custom certificate or public-key verification could therefore accept a certificate that the callback was intended to reject. This release preserves TLS options when creating per-origin dispatchers.

Cache poisoning and cross-user disclosure through cross-origin redirects

CVE-2026-109829 · GHSA-4w7w-5xrc-9h26

When an originless Agent combined redirect and shared-cache interceptors as compose(redirect(), cache()), a response from a cross-origin redirect could be stored under the original URL. This could allow persistent cache poisoning or disclosure of user-specific responses to later callers. This release verifies the response origin before caching and preserves redirect-hop cache-control policy.

Denial of service through excessive Content-Encoding values

CVE-2026-109869 · GHSA-xjj6-f33q-929c

A malicious HTTP server could crash the Node.js process by returning more than five content codings and closing the connection before sending the body. Although fetch() rejected the response, an error from an orphaned internal stream could remain unhandled. This release validates the content-encoding chain before creating the body stream and aborts oversized chains safely.

Medium severity

Denial of service through the decompress interceptor

CVE-2026-87029 · GHSA-55wc-3pg8-jfw6

An exception thrown by a downstream response handler from an asynchronous decompression callback could escape as an uncaught exception. A server could trigger this when decompress was composed with a handler such as dump with a size limit. This release converts downstream handler exceptions into per-request errors.

Subresource Integrity bypass with non-lowercase algorithm tokens

CVE-2026-109841 · GHSA-f72v-6w45-q472

fetch() treated valid mixed-case or uppercase SRI algorithm tokens, such as SHA256, as unknown and could accept a response whose body did not match the configured digest. This release normalizes algorithm tokens before validation and digest selection.

Denial of service through unbounded EventSource parser state

CVE-2026-109924 · GHSA-4qv8-2p9j-2685

A malicious Server-Sent Events endpoint could exhaust process memory by sending many tiny data: fields without completing an event, or by splitting an unfinished line across many chunks. This release bounds retained EventSource parser state, including field counts, buffered chunks, unfinished-line length, and retained field data.

Denial of service through unbounded automatic WebSocket PONG buffering

CVE-2026-109932 · GHSA-9fm3-97px-rjf6

A malicious WebSocket server could exhaust process memory by flooding the client with PING frames while not reading the automatic PONG responses. undici previously ignored socket backpressure and allowed the outbound queue to grow without bound. This release pauses frame parsing when PONG writes encounter backpressure and resumes after the socket drains.

What's Changed

• test: disable timeouts in h2 high concurrency regression by @mcollina in #5893
• test: reduce retry-after invalid date timing flake by @mcollina in #5892
• [v7.x] fix(session cache): fix bug in tls session caching (#5882) by @mrityunjay-pandey in #6017
• [Backport v7.x] fix: avoid unbounded recursion in Set-Cookie attribute parser by @janneh in #5997
• [v7.x] fix(cookies): backport #5663, #5808 and #5832 by @mrityunjay-pandey in #6019

New Contributors

• @janneh made their first contribution in #5997

Full Changelog: v7.30.0...v7.30.1

Security fixes

High severity

Denial of service via TLS 1.2 certificate-changing renegotiation

CVE-2026-87018 · GHSA-qrxm-fqhp-jwvm

A malicious or compromised HTTPS server could crash the Node.js process by initiating TLS 1.2 renegotiation and presenting a different, CA-trusted certificate whose hostname did not match the requested host. The resulting socket error reached an assertion in undici's HTTP/1.1 and HTTP/2 connection handling. This release handles post-connect certificate errors without terminating the process.

TLS certificate validation bypass through dropped Agent options

CVE-2026-109383 · GHSA-2m5v-pch6-74hx

Agent used a JSON-based clone for constructor options, which silently removed function-valued TLS options such as checkServerIdentity. Applications relying on custom certificate or public-key verification could therefore accept a certificate that the callback was intended to reject. This release preserves TLS options when creating per-origin dispatchers.

Denial of service through excessive Content-Encoding values

CVE-2026-109869 · GHSA-xjj6-f33q-929c

A malicious HTTP server could crash the Node.js process by returning more than five content codings and closing the connection before sending the body. Although fetch() rejected the response, an error from an orphaned internal stream could remain unhandled. This release validates the content-encoding chain before creating the body stream and aborts oversized chains safely.

Medium severity

Denial of service through unbounded EventSource parser state

CVE-2026-109924 · GHSA-4qv8-2p9j-2685

A malicious Server-Sent Events endpoint could exhaust process memory by sending many tiny data: fields without completing an event, or by splitting an unfinished line across many chunks. This release bounds retained EventSource parser state, including field counts, buffered chunks, unfinished-line length, and retained field data.

Denial of service through unbounded automatic WebSocket PONG buffering

CVE-2026-109932 · GHSA-9fm3-97px-rjf6

A malicious WebSocket server could exhaust process memory by flooding the client with PING frames while not reading the automatic PONG responses. undici previously ignored socket backpressure and allowed the outbound queue to grow without bound. This release pauses frame parsing when PONG writes encounter backpressure and resumes after the socket drains.

What's Changed

• [v6.x] fix(fetch): fix aborting Streams (#3754) by @mrityunjay-pandey in #6000

Full Changelog: v6.29.0...v6.29.1

What's Changed

• fix: restore build:wasm npm script by @mcollina in #6009
• test: add unexpected disconnect guards to http2-body-delete.js by @Kesavamoorthig06 in #5970

New Contributors

• @Kesavamoorthig06 made their first contribution in #5970

Full Changelog: v8.12.0...v8.12.1

What's Changed

• fix(cookies): ignore a numeric expires outside the Date range by @xia-chao in #5832
• fix(http2): pause bodyTimeout while applying backpressure by @jasnell in #5884
• fix(cache): track cached response abort state by @mcollina in #5820
• fix(deduplicate): make terminal callbacks exception-safe by @mcollina in #5838
• fix(decompress): stop inflating compress and x-compress by @luantaraschi in #5665
• fix(cache): evict least recently used entries in MemoryCacheStore by @jasnell in #5869
• fix(eventsource): fix redirect targets in eventsource by @jasnell in #5878
• fix(redirect): fix throwOnMaxRedirect edge by @jasnell in #5879
• fix: normalize HTTP/2 headers for legacy dispatch handlers by @Knowzzz in #5867
• fix(session cache): fix bug in tls session caching by @jasnell in #5882
• docs: fix relative links broken by the README move by @v1teka in #5843
• fix(redirect): add error code to max redirects error by @mcollina in #5895
• fix(eventsource): fix retry wrap bug by @jasnell in #5875
• fix(retry): keep request headers when resuming a download by @jasnell in #5870
• fix(proxyagent): correct handling of the host header by @jasnell in #5868
• fix(http1): fix handling of 204/304 responses by @jasnell in #5864
• test: add unexpected disconnect guards to two more h2 tests by @zeexzeex in #5825
• fix(cache): preserve 304 response event order with async stores by @marcopiraccini in #5797
• fix(dns): handle a null pick, and stop failing over to an expired record by @datrixlab in #5791
• fix: keep a header named proto across features by @luantaraschi in #5688
• ci: exclude tests from CodeQL analysis by @mcollina in #5905
• fix(pool): ensure that removed clients don't pick up requests by @jasnell in #5881
• feat: Added @perseveranza-pets/milo as alternative experimental HTTP parser by @ShogunPanda in #5492
• extractBody fixes 2 by @KhafraDev in #5926
• reenable cachestorage wpts by @KhafraDev in #5907
• fix(fetch): parse language tag in filename* parameters by @fallintoplace in #5908
• fix(client): preserve tracked response header field boundaries by @ronag in #5940
• fix(http1): fixup strictContentLength handling by @jasnell in #5897
• feat(cache): compress big sqlite cache entries with zstd by @mcollina in #5744
• fix(eventsource): enforce maxEventSize on unterminated lines by @mcollina in #5814
• limit zstd window size to 8 MB by @KhafraDev in #5955
• test: add unexpected disconnect guards to http2-body.js by @GhostCoder6969 in #5914
• test: fix "specifiy" typo in cache interceptor test by @ump45nose in #5922
• Wpt/wpt runner fixes by @KhafraDev in #5959
• fix(h2): unref a session detached by GOAWAY with no open streams by @kjsik11 in #5960
• feat: Throw an error when WebAssembly is not available. by @ShogunPanda in #5966
• chore: Vendor milo 0.9.0. by @ShogunPanda in #5954
• build(deps-dev): bump ws from 8.21.3 to 8.22.0 by @dependabot[bot] in #5968
• build(deps-dev): bump undici from 6.28.0 to 6.29.0 by @dependabot[bot] in #5933
• fix(typemap): .md -> .html by @avivkeller in #5602
• build(deps): bump js-yaml from 4.1.1 to 4.3.2 by @dependabot[bot] in #5810
• build(deps): bump brace-expansion by @dependabot[bot] in #5934
• build(deps-dev): bump fast-check from 4.10.1 to 4.10.2 by @dependabot[bot] in #5921
• test(fetch): settle h2 internal stream errors by @Yahiro025 in #5927
• docs(errors): clarify timeout error codes and related options by @theamodhshetty in #4856
• fix(interceptor): limit response error body size by @mcollina in #5942
• build(deps): bump codecov/codecov-action from 7.0.0 to 7.1.1 by @dependabot[bot] in #5946
• build(deps): bump hendrikmuhs/ccache-action from 1.2.23 to 1.2.24 by @dependabot[bot] in #5951
• build(deps): bump github/codeql-action/analyze from 4.37.9 to 4.38.2 by @dependabot[bot] in #5952
• build(deps): bump github/codeql-action/autobuild from 4.37.9 to 4.38.2 by @dependabot[bot] in #5950
• build(deps): bump github/codeql-action/init from 4.37.9 to 4.38.2 by @dependabot[bot] in #5948
• build(deps): bump github/codeql-action/upload-sarif from 4.37.9 to 4.38.2 by @dependabot[bot] in #5947
• build(deps): bump actions/checkout from 7.0.0 to 7.0.1 by @dependabot[bot] in #5630
• fix(http1): reset connections for no-body transfer encoding by @mcollina in #5941
• fix: exclude experimental milo from node.js core bundle by @mcollina in #5935
• test: re-enable HTTP/2 churn test on Node.js 26 by @mcollina in #5961
• test: keep the h2c unix socket path within sun_path limits by @mcollina in #5978
• fix(cache): preserve abort reasons after completion by @domenic in #5958
• test: update milo paths in bundle-parser test by @mcollina in #5979
• fix(cache): always treat zero-lifetime entries as stale by @mcollina in #5980
• build(deps): bump step-security/harden-runner from 2.21.0 to 2.21.1 by @dependabot[bot] in #5949
• fix(websocket,eventsource): keep receive limits behind dispatcher wrappers by @jasnell in #5896
• fix(http2): enforce max concurrent streams by @jasnell in #5885
• docs: sync WG collaborators with nodejs/undici team by @mcollina in #5991
• build(deps-dev): bump @fastify/busboy from 3.2.2 to 3.2.3 by @dependabot[bot] in #6005
• fix: ignore missing release ref during cleanup by @mcollina in #5891
• fix: reject unsupported FormData request bodies by @mcollina in #5913
• split wpt out of npm test by @mcollina in #5588

New Contributors

• @xia-chao made their first contribution in #5832
• @jasnell made their first contribution in #5884
• @Knowzzz made their first contribution in #5867
• @v1teka made their first contribution in #5843
• @datrixlab made their first contribution in #5791
• @fallintoplace made their first contribution in #5908
• @GhostCoder6969 made their first contribution in #5914
• @ump45nose made their first contribution in #5922

Full Changelog: v8.11.2...v8.12.0

What's Changed

• [Backport v7.x] fix: selectively re-enable SIMD for ppc64 by @github-actions[bot] in #5794
• Backport upgrade diagnostics lifecycle fixes to v7.x by @BridgeAR in #5783
• [Backport v7.x] fix: honor backpressure in decompression interceptor by @mcollina in #5837
• fix: close rejected HTTP/2 WebSocket streams on v7.x by @mcollina in #5876
• test(fetch): make pull-dont-push exceed any socket buffer by @mcollina in #5889

Full Changelog: v7.29.1...v7.30.0

What's Changed

• [v6.x] fix(retry): settle exposed body on terminal failure by @mcollina in #5778
• Backport upgrade diagnostics lifecycle fixes to v6.x by @BridgeAR in #5833
• test: synchronize the issue-3356 body timeout by @BridgeAR in #5834

Full Changelog: v6.28.1...v6.29.0

What's Changed

• fix: close rejected HTTP/2 WebSocket handshake streams by @mcollina in #5873
• fix: avoid reconnecting aborted requests by @Junaid-PK in #5846

New Contributors

• @Junaid-PK made their first contribution in #5846

Full Changelog: v8.11.1...v8.11.2

What's Changed

• deslopify websocket test by @KhafraDev in #5851
• Revert "fix: preserve HTTP/2 for legacy fetch consumers" by @mcollina in #5860
• fix websocketstream bugs by @KhafraDev in #5863
• fix hang on 3xx response with large body by @KhafraDev in #5850
• docs: warn about buffering response bodies by @mcollina in #5872
• test: cover native fetch gzip decoding through the legacy bridge by @mcollina in #5874

Full Changelog: v8.11.0...v8.11.1