CVE-2026-84961

NameCVE-2026-84961
Descriptionundici'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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
node-undici (PTS)bookworm5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4vulnerable
bookworm (security)5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3vulnerable
trixie7.3.0+dfsg1+~cs24.12.11-1vulnerable
forky, sid8.9.0+dfsg+~cs3.2.0-1vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
node-undicisource(unstable)(unfixed)

Notes

https://github.com/nodejs/undici/security/advisories/GHSA-w293-vg96-wgc3

Search for package or bug name: Reporting problems