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Medium · 6.5 CVE-2026-84933 EUVD-2026-71518GHSA-2jfj-6hjv-fm6j

undici vulnerable to cross-user cookie disclosure via Set-Cookie caching in shared caches

Published Sep 4, 2026 · Updated Sep 4, 2026 · Assigned by openjs

Description

undici's cache interceptor does not handle the Set-Cookie response header anywhere in its cache path, so it neither refuses to store nor strips that header. In shared cache mode, which is the default, an otherwise cacheable response that carries a Set-Cookie header, for example one marked with a public and max-age directive, is stored and then re-served to a later caller that matches the same cache key. As a result one caller's cookie is disclosed to a different caller, and an untrusted server can inject cookies into cached responses served to all subsequent callers. This violates the requirement that a shared cache must not store cookies. This affects undici versions from 7.0.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. Users should upgrade to undici 7.29.1 or 8.10.2.

Affected products

VendorProductAffectedFixed
undici undici 7.0.0 – < 7.29.1, 8.0.0 – < 8.10.2 7.29.1

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 node-undici 8.10.2+dfsg+~cs3.2.2-1 —
Debian 13 node-undici No fix yet —
Debian 12 node-undici No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 node-undici No fix yet —
Ubuntu 26.04 LTS node-undici No fix yet —
Ubuntu 24.04 LTS node-undici No fix yet —
ReleasePackageFixed inAdvisory
Red Hat Hardened Images 1 grafana12.4 12.4.10-0.2.hum1 RHSA-2026:66008
Red Hat Hardened Images 1 nodejs24 +6 24.18.1-0.2.2.hum1 RHSA-2026:54438
Red Hat Hardened Images 1 nodejs24-npm 11.16.0-1.24.18.1.0.2.2.hum1 RHSA-2026:54438
Red Hat Hardened Images 1 nodejs26 +6 26.7.0-1.5.2.hum1 RHSA-2026:54389
Red Hat Hardened Images 1 nodejs26-npm 11.19.0-1.26.7.0.1.5.2.hum1 RHSA-2026:54389
Red Hat Hardened Images 1 v8-14.6-devel 14.6.202.34-1.26.7.0.1.5.2.hum1 RHSA-2026:54389
ReleasePackageFixed inAdvisory
openSUSE Tumbleweed pi-coding-agent 0.87.1-1.1 openSUSE-SU-2026:11884-1
openSUSE Leap 16.0 pi-coding-agent 1.0.4-bp160.1.1 openSUSE-SU-2026:22111-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 nodejs24 +4 1:24.21.0-1.amzn2023.0.1 ALAS2023-2026-3107
Amazon Linux 2023 nodejs24-npm 1:11.19.0-1.24.21.0.1.amzn2023.0.1 ALAS2023-2026-3107
Amazon Linux 2023 v8-13.6-devel 3:13.6.233.17-1.24.21.0.1.amzn2023.0.1 ALAS2023-2026-3107

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling code-server 4.139.1-r2 —
Wolfi rolling lerna 10.0.1-r11 —
Wolfi rolling node-gyp 13.0.2-r1 —
Wolfi rolling prism 5.16.0-r14 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm undici >= 7.0.0, < 7.29.1 7.29.1 GHSA-2jfj-6hjv-fm6j
npm undici >= 8.0.0, < 8.10.2 8.10.2 GHSA-2jfj-6hjv-fm6j

Advisories 7

References