undici's BalancedPool constructor passes its entire options object through an internal deep-clone that serializes and reparses the value as JSON. Because JSON cannot represent functions, any function-valued TLS option, such as a caller-supplied checkServerIdentity callback or a custom connector inside the connect option, is silently discarded before it reaches the TLS layer. As a result a peer whose certificate the application's custom checkServerIdentity was written to reject, but which still passes Node's default hostname and chain checks, is accepted when reached through BalancedPool. The Client, Pool, and Agent dispatchers are not affected because they extract the connect and tls options before cloning. This affects undici versions from 7.24.1 up to 7.29.1 and from 8.0.0 up to 8.10.2, and only when the application supplies a function-valued connect or tls option to BalancedPool. Users should upgrade to undici 7.29.1 or 8.10.2.
CVSS Details
- CVSS 3.1 Base Score: 9.1
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade nodejs24-docsUpgrade nodejs24-npmUpgrade nodejs24-develUpgrade nodejs24-libs-debuginfoUpgrade nodejs24-libsUpgrade nodejs24-debugsourceUpgrade nodejs24-full-i18nUpgrade nodejs24Upgrade v8-13.6-develUpgrade nodejs24-debuginfo | Sep 30, 2026 | Sep 4, 2026 |
| Redhat_linux | — | Upgrade nodejs-libsNo solution existsUpgrade nodejs24-libs-debuginfoUpgrade nodejs-packagingUpgrade npmUpgrade nodejs24-docsUpgrade nodejs-nodemonUpgrade nodejs-full-i18nUpgrade nodejs24-npmUpgrade nodejs24-libsUpgrade nodejs24-debugsourceUpgrade nodejs-debuginfoUpgrade nodejs24-full-i18nUpgrade nodejs24Upgrade nodejs-develUpgrade nodejs24-debuginfoUpgrade v8-13.6-develUpgrade nodejs-packaging-bundlerUpgrade nodejsUpgrade nodejs-libs-debuginfoUpgrade nodejs-debugsourceUpgrade nodejs-docsUpgrade nodejs24-devel | Sep 7, 2026 | Sep 4, 2026 |
| Rocky_linux | — | Upgrade nodejsUpgrade nodejs-full-i18nUpgrade nodejs-debugsourceUpgrade nodejs24-develUpgrade nodejs24-libsUpgrade nodejs24Upgrade nodejs24-debugsourceUpgrade nodejs-libsUpgrade nodejs-libs-debuginfoUpgrade nodejs-debuginfoUpgrade nodejs24-debuginfoUpgrade nodejs24-full-i18nUpgrade v8-13.6-develUpgrade nodejs24-libs-debuginfoUpgrade nodejs-devel | Oct 5, 2026 | Oct 1, 2026 |
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