{"schema":"threatline.record/2","record":{"id":"CVE-2026-84961","aliases":["GHSA-w293-vg96-wgc3"],"summary":"undici vulnerable to TLS certificate validation bypass via dropped connect options in BalancedPool","details":"### Impact\n\nundici's `BalancedPool` passes its constructor options through a JSON-based deep clone (`JSON.parse(JSON.stringify(...))`) before forwarding them to each per-upstream `Pool`. JSON cannot represent functions, so a caller-supplied `connect` or `tls` option containing a `checkServerIdentity` callback (or a custom connector function) 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 `BalancedPool`. `Client`, `Pool`, `Agent`, and `RoundRobinPool` destructure `connect`/`tls` before the clone and are not affected. Only applications that use `BalancedPool` with a function-valued `connect`/`tls` option (such as a custom `checkServerIdentity` or connector) are affected.\n\n### Patches\n\nUpgrade to `7.29.1` or `8.10.2`. `BalancedPool` now preserves the `connect` and `tls` options outside the JSON clone, so custom TLS verification callbacks are forwarded to each upstream unchanged.\n\n### Workarounds\n\nUse `Client`, `Pool`, or `Agent` instead of `BalancedPool` for connections that rely on a custom `checkServerIdentity` or connector, until upgraded.","categories":["Libraries & packages"],"product":"undici","vendor":"undici","ecosystem":"npm","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-w293-vg96-wgc3","source_modified_at":"2026-09-29T18:17:16Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"undici"},"range":">= 7.24.1, < 7.29.1"},{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-w293-vg96-wgc3","source_modified_at":"2026-09-29T18:17:16Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"undici"},"range":">= 8.0.0, < 8.10.2"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84961","source_modified_at":"2026-09-04T18:37:44.620Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"undici","vendor":"undici","versions":[{"lessThan":"7.29.1","status":"affected","version":"7.24.1","versionType":"semver"},{"status":"unaffected","version":"7.29.1","versionType":"semver"},{"lessThan":"8.10.2","status":"affected","version":"8.0.0","versionType":"semver"},{"status":"unaffected","version":"8.10.2","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-w293-vg96-wgc3","source_modified_at":"2026-09-29T18:28:14.915098573Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"7.24.1"},{"fixed":"7.29.1"}]}],"versions":[]},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-w293-vg96-wgc3","source_modified_at":"2026-09-29T18:28:14.915098573Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"8.0.0"},{"fixed":"8.10.2"}]}],"versions":[]}],"fixed_versions":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-w293-vg96-wgc3","source_modified_at":"2026-09-29T18:17:16Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"undici"},"version":"7.29.1"},{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-w293-vg96-wgc3","source_modified_at":"2026-09-29T18:17:16Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"undici"},"version":"8.10.2"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84961","source_modified_at":"2026-09-04T18:37:44.620Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"undici","ecosystem":null},"version":"7.29.1","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84961","source_modified_at":"2026-09-04T18:37:44.620Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"undici","ecosystem":null},"version":"8.10.2","basis":"first unaffected version stated in the CVE record"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-w293-vg96-wgc3","source_modified_at":"2026-09-29T18:28:14.915098573Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"version":"7.29.1"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-w293-vg96-wgc3","source_modified_at":"2026-09-29T18:28:14.915098573Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"version":"8.10.2"}],"cvss":7.4,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00146,"percentile":0.03549,"score_date":"2026-10-23"},"published_at":"2026-09-04T16:47:55.724Z","modified_at":"2026-09-29T18:28:14.915098573Z","provenance":[{"source":"GitHub Advisory Database","url":"https://github.com/advisories/GHSA-w293-vg96-wgc3","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-09-29T18:17:16Z"},{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-84961","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-09-04T18:37:44.620Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-w293-vg96-wgc3","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-09-29T18:28:14.915098573Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-84961","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["GitHub Advisory Database","CVE List","OSV","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/nodejs/undici/security/advisories/GHSA-w293-vg96-wgc3"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84961","source":"GitHub Advisory Database"},{"url":"https://github.com/nodejs/undici/commit/8f5868fbdbc8f1146dfc1bcd1f2d117790141390","source":"GitHub Advisory Database"},{"url":"https://github.com/nodejs/undici/commit/f690157d728508652fef14673630c71515123e96","source":"GitHub Advisory Database"},{"source":"CVE List","url":"https://cna.openjsf.org/security-advisories.html"},{"url":"https://github.com/nodejs/undici/releases/tag/v7.29.1","source":"GitHub Advisory Database"},{"url":"https://github.com/nodejs/undici/releases/tag/v8.10.2","source":"GitHub Advisory Database"},{"url":"https://github.com/advisories/GHSA-w293-vg96-wgc3","source":"GitHub Advisory Database"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"total","assessed_at":"2026-09-04T18:35:57.858790Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"ecosystem","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-09-29T18:28:14.915098573Z","content_hash":"42d8dc021492551b5d91c5cfd66e7f790c589f8fb55fec5f705f8a161cc7089d"}}