CVE-2026-84961
Description
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
undicinpm | >= 7.24.1, < 7.29.1 | 7.29.1 |
undicinpm | >= 8.0.0, < 8.10.2 | 8.10.2 |
Affected products
19- osv-coords17 versionspkg:rpm/almalinux/npmpkg:rpm/opensuse/pi-coding-agent&distro=openSUSE%20Tumbleweedpkg:rpm/almalinux/nodejs24pkg:rpm/almalinux/nodejs24-develpkg:rpm/almalinux/nodejs24-docspkg:rpm/almalinux/nodejs24-full-i18npkg:rpm/almalinux/nodejs24-libspkg:rpm/almalinux/nodejs24-npmpkg:rpm/almalinux/nodejspkg:rpm/almalinux/nodejs-develpkg:rpm/almalinux/nodejs-docspkg:rpm/almalinux/nodejs-full-i18npkg:rpm/almalinux/nodejs-libspkg:rpm/almalinux/nodejs-nodemonpkg:rpm/almalinux/nodejs-packagingpkg:rpm/almalinux/nodejs-packaging-bundlerpkg:rpm/almalinux/v8-13.6-devel
< 1:11.19.0-1.24.21.0.1.module_el9.8.0+321+1555b6a2+ 16 more
- (no CPE)range: < 1:11.19.0-1.24.21.0.1.module_el9.8.0+321+1555b6a2
- (no CPE)range: < 0.87.1-1.1
- (no CPE)range: < 1:24.21.0-1.el10_2
- (no CPE)range: < 1:24.21.0-1.el10_2
- (no CPE)range: < 1:24.21.0-1.el10_2
- (no CPE)range: < 1:24.21.0-1.el10_2
- (no CPE)range: < 1:24.21.0-1.el10_2
- (no CPE)range: < 2:11.19.0-1.24.21.0.1.el10_2
- (no CPE)range: < 1:24.21.0-1.module_el9.8.0+321+1555b6a2
- (no CPE)range: < 1:24.21.0-1.module_el9.8.0+321+1555b6a2
- (no CPE)range: < 1:24.21.0-1.module_el9.8.0+321+1555b6a2
- (no CPE)range: < 1:24.21.0-1.module_el9.8.0+321+1555b6a2
- (no CPE)range: < 1:24.21.0-1.module_el9.8.0+321+1555b6a2
- (no CPE)range: < 3.1.14-3.module_el9.8.0+292+f4eaf8b2
- (no CPE)range: < 2021.06-6.module_el9.7.0+209+ecf6523e
- (no CPE)range: < 2021.06-6.module_el9.7.0+209+ecf6523e
- (no CPE)range: < 3:13.6.233.17-1.24.21.0.1.module_el9.8.0+321+1555b6a2
Patches
Vulnerability mechanics
References
8- cna.openjsf.org/security-advisories.htmlnvdThird Party AdvisoryWEB
- github.com/advisories/GHSA-w293-vg96-wgc3ghsaADVISORY
- github.com/nodejs/undici/security/advisories/GHSA-w293-vg96-wgc3nvdMitigationVendor AdvisoryWEB
- nvd.nist.gov/vuln/detail/CVE-2026-84961ghsaADVISORY
- github.com/nodejs/undici/commit/8f5868fbdbc8f1146dfc1bcd1f2d117790141390ghsaWEB
- github.com/nodejs/undici/commit/f690157d728508652fef14673630c71515123e96ghsaWEB
- github.com/nodejs/undici/releases/tag/v7.29.1ghsaWEB
- github.com/nodejs/undici/releases/tag/v8.10.2ghsaWEB
News mentions
0No linked articles in our index yet.