{"id":"GHSA-2m5v-pch6-74hx","summary":"undici vulnerable to TLS certificate validation bypass via dropped tls options in Agent","details":"### Impact\n\nundici's `Agent` passes its constructor options through a JSON-based deep clone (`JSON.parse(JSON.stringify(...))`) before forwarding them to each per-origin `Pool`. JSON cannot represent functions, so a caller-supplied `tls` option containing a `checkServerIdentity` callback is silently dropped before it reaches the TLS layer. As a result, a TLS peer whose certificate a custom `checkServerIdentity` was written to reject, but which passes Node's default hostname and chain checks, is silently accepted when the request is made through `Agent`. Because `Agent` is the default dispatcher behind `request`, `fetch`, and `setGlobalDispatcher`, this is the path most applications use. `EnvHttpProxyAgent` is also affected on its direct and `NO_PROXY` routes, which delegate to an internal `Agent`.\n\nOnly applications that pass a function-valued `tls` option (such as a custom `checkServerIdentity` for certificate or public-key pinning) are affected. Passing the same options through `connect` is not affected. This is the `Agent` counterpart of the `BalancedPool` certificate validation bypass fixed in CVE-2026-84961.\n\n### Patches\n\nUpgrade to undici `6.29.1`, `7.30.1`, or `8.12.2`. `Agent` now preserves the `tls` option outside the JSON clone, so custom TLS verification callbacks are forwarded to each origin unchanged.\n\n### Workarounds\n\nPass the TLS options through `connect` instead of `tls`. For proxied `EnvHttpProxyAgent` destinations, use `requestTls` / `proxyTls`.","aliases":["CVE-2026-109383"],"modified":"2026-10-27T19:15:22.407771210Z","published":"2026-10-27T19:02:26Z","database_specific":{"github_reviewed_at":"2026-10-27T19:02:26Z","nvd_published_at":"2026-10-15T19:17:20Z","cwe_ids":["CWE-295"],"severity":"HIGH","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/nodejs/undici/security/advisories/GHSA-2m5v-pch6-74hx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-109383"},{"type":"WEB","url":"https://github.com/nodejs/undici/commit/04cb74b1db131ff8f5b4557dce811cbf5f4664b4"},{"type":"WEB","url":"https://github.com/nodejs/undici/commit/8c59f6b302898cb2e9b0f7962cd7212b6e597c9f"},{"type":"WEB","url":"https://github.com/nodejs/undici/commit/f75eac00ac177f7b2e6c8bfbd52d4113164286e6"},{"type":"WEB","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"PACKAGE","url":"https://github.com/nodejs/undici"},{"type":"WEB","url":"https://github.com/nodejs/undici/releases/tag/v6.29.1"},{"type":"WEB","url":"https://github.com/nodejs/undici/releases/tag/v7.30.1"},{"type":"WEB","url":"https://github.com/nodejs/undici/releases/tag/v8.12.2"}],"affected":[{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"4.0.0"},{"fixed":"6.29.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-2m5v-pch6-74hx/GHSA-2m5v-pch6-74hx.json"}},{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"7.0.0"},{"fixed":"7.30.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-2m5v-pch6-74hx/GHSA-2m5v-pch6-74hx.json"}},{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"8.0.0"},{"fixed":"8.12.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-2m5v-pch6-74hx/GHSA-2m5v-pch6-74hx.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"}]}