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OpenAdvisories
Low · 3.7 CVE-2026-11525 EUVD-2026-37758GHSA-g8m3-5g58-fq7m

undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching

Published Jun 17, 2026 · Updated Jun 17, 2026 · Assigned by openjs

Description

Impact:
When undici parses a Set-Cookie header, it accepts any SameSite attribute value that contains Strict, Lax, or None as a substring, rather than the case-insensitive exact match specified by RFC 6265. Non-spec values are silently mapped to one of the three standard tokens. For example, SameSite=NoneOfYourBusiness is parsed as None (the most permissive setting), and SameSite=StrictLax is parsed as Lax (a downgrade from Strict).

Affected applications are those that consume Set-Cookie headers from server responses (for example via undici's fetch or proxy code paths) and then forward or rely on the parsed sameSite attribute. A malicious or non-compliant server can coerce the consumer's view of a cookie's SameSite policy to a weaker value, silently degrading the SameSite enforcement the cookie is supposed to provide.

This was introduced in undici 5.15.0 when the cookies feature was added.

Patches:
Upgrade to undici v6.26.0, v7.28.0 or v8.5.0.

Workarounds:
After parsing a Set-Cookie header, validate that the resulting sameSite attribute is one of 'Strict', 'Lax', or 'None' (exact, case-insensitive) before forwarding or relying on it.

Affected products

VendorProductAffectedFixed
undici undici < 6.26.0, 7.0.0 – < 7.28.0, 8.0.0 – < 8.5.0 6.26.0

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 8.5.0+dfsg+~cs3.2.0-1 —
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 25.10 node-undici No fix yet —
Ubuntu 24.04 LTS node-undici No fix yet —
ReleasePackageFixed inAdvisory
RHEL 10 nodejs +5 1:22.23.1-2.el10_2 RHSA-2026:35842
RHEL 10 nodejs-npm 1:10.9.8-1.22.23.1.2.el10_2 RHSA-2026:35842
RHEL 10 nodejs24 +4 1:24.18.0-1.el10_2 RHSA-2026:35841
RHEL 10 nodejs24-npm 1:11.16.0-1.24.18.0.1.el10_2 RHSA-2026:35841
RHEL 9 nodejs +4 1:22.23.1-1.module+el9.8.0+24457+996af7aa RHSA-2026:35892, RHSA-2026:35891
RHEL 9 nodejs-nodemon 3.0.1-1.module+el9.8.0+24156+bb41d456 RHSA-2026:35892, RHSA-2026:35891
RHEL 9 nodejs-packaging +1 2021.06-6.module+el9.8.0+24156+bb41d456 RHSA-2026:35892, RHSA-2026:35891
RHEL 9 npm 1:10.9.8-1.22.23.1.1.module+el9.8.0+24457+996af7aa RHSA-2026:35892, RHSA-2026:35891
RHEL 9 v8-12.4-devel 3:12.4.254.21-1.22.23.1.1.module+el9.8.0+24457+996af7aa RHSA-2026:35892
RHEL 9 v8-13.6-devel 3:13.6.233.17-1.24.18.0.1.module+el9.8.0+24456+b244c3b4 RHSA-2026:35891
RHEL 8 nodejs +4 1:22.23.1-1.module+el8.10.0+24500+8eb51621 RHSA-2026:41947, RHSA-2026:39868
RHEL 8 nodejs-nodemon 3.0.1-1.module+el8.10.0+24500+8eb51621 RHSA-2026:41947, RHSA-2026:39868
RHEL 8 nodejs-packaging +1 2021.06-6.module+el8.10.0+24190+49a46c75 RHSA-2026:41947, RHSA-2026:39868
RHEL 8 npm 1:10.9.8-1.22.23.1.1.module+el8.10.0+24500+8eb51621 RHSA-2026:41947, RHSA-2026:39868
RHEL 8 v8-12.4-devel 3:12.4.254.21-1.22.23.1.1.module+el8.10.0+24500+8eb51621 RHSA-2026:41947
RHEL 8 v8-13.6-devel 3:13.6.233.17-1.24.18.0.1.module+el8.10.0+24481+7a71fac8 RHSA-2026:39868
Show 1 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Red Hat Hardened Images 1 nodejs24 +6 1:24.18.0-0.3.hum1 RHSA-2026:38236
Red Hat Hardened Images 1 nodejs24-npm 1:11.16.0-1.24.18.0.0.3.hum1 RHSA-2026:38236
Red Hat Hardened Images 1 nodejs26 +6 1:26.5.0-1.5.hum1 RHSA-2026:45783
Red Hat Hardened Images 1 nodejs26-npm 1:11.17.0-1.26.5.0.1.5.hum1 RHSA-2026:45783
Red Hat Hardened Images 1 v8-13.6-devel 3:13.6.233.17-1.24.18.0.0.3.hum1 RHSA-2026:38236

AlmaLinux

Errata ↗
ReleasePackageFixed inAdvisory
AlmaLinux 10 nodejs +4 1:22.23.1-2.el10_2 ALSA-2026:35842
AlmaLinux 10 nodejs-npm 1:10.9.8-1.22.23.1.2.el10_2 ALSA-2026:35842
AlmaLinux 10 nodejs24 +4 1:24.18.0-1.el10_2 ALSA-2026:35841
AlmaLinux 10 nodejs24-npm 1:11.16.0-1.24.18.0.1.el10_2 ALSA-2026:35841
AlmaLinux 9 nodejs +4 1:22.23.1-1.module_el9.8.0+276+8b329b47 ALSA-2026:35892, ALSA-2026:35891
AlmaLinux 9 nodejs-nodemon 3.0.1-1.module_el9.7.0+208+fb06c0ab ALSA-2026:35892, ALSA-2026:35891
AlmaLinux 9 nodejs-packaging +1 2021.06-6.module_el9.7.0+209+ecf6523e ALSA-2026:35892, ALSA-2026:35891
AlmaLinux 9 npm 1:10.9.8-1.22.23.1.1.module_el9.8.0+276+8b329b47 ALSA-2026:35892, ALSA-2026:35891
AlmaLinux 9 v8-12.4-devel 3:12.4.254.21-1.22.23.1.1.module_el9.8.0+276+8b329b47 ALSA-2026:35892
AlmaLinux 9 v8-13.6-devel 3:13.6.233.17-1.24.18.0.1.module_el9.8.0+277+61fc613e ALSA-2026:35891
AlmaLinux 8 nodejs +4 1:22.23.1-1.module_el8.10.0+4231+1bf2f855 ALSA-2026:41947, ALSA-2026:39868
AlmaLinux 8 nodejs-nodemon 3.0.1-1.module_el8.10.0+3956+47c9ee9f ALSA-2026:41947, ALSA-2026:39868
AlmaLinux 8 nodejs-packaging +1 2021.06-6.module_el8.10.0+4086+70facd4a ALSA-2026:41947, ALSA-2026:39868
AlmaLinux 8 npm 1:10.9.8-1.22.23.1.1.module_el8.10.0+4231+1bf2f855 ALSA-2026:41947, ALSA-2026:39868
AlmaLinux 8 v8-12.4-devel 3:12.4.254.21-1.22.23.1.1.module_el8.10.0+4231+1bf2f855 ALSA-2026:41947
AlmaLinux 8 v8-13.6-devel 3:13.6.233.17-1.24.18.0.1.module_el8.10.0+4228+2938bc94 ALSA-2026:39868

Rocky Linux

Errata ↗
ReleasePackageFixed inAdvisory
Rocky Linux 10 nodejs22 1:22.23.1-2.el10_2 RLSA-2026:35842
Rocky Linux 10 nodejs24 1:24.18.0-1.el10_2 RLSA-2026:35841
Rocky Linux 9 nodejs-nodemon 3.0.1-1.module+el9.7.0+40022+9ecc286c RLSA-2026:35892, RLSA-2026:35891
Rocky Linux 9 nodejs-packaging 2021.06-6.module+el9.7.0+40052+e32ea525 RLSA-2026:35892, RLSA-2026:35891
Rocky Linux 8 nodejs 1:24.18.0-1.module+el8.10.0+40252+a58646bc RLSA-2026:39868
Rocky Linux 8 nodejs-nodemon 3.0.1-1.module+el8.9.0+1760+903d54b9 RLSA-2026:41947, RLSA-2026:39868
Rocky Linux 8 nodejs-packaging 2021.06-6.module+el8.10.0+40048+6d99f608 RLSA-2026:41947, RLSA-2026:39868
ReleasePackageFixed inAdvisory
SLES 15 SP7 nodejs22 22.23.0-150700.3.12.1 SUSE-SU-2026:2695-1
SLES 15 SP7 nodejs24 24.17.0-150700.15.11.1 SUSE-SU-2026:2633-1
SLES 15 SP6 nodejs20 20.20.2-150600.3.21.1 SUSE-SU-2026:3929-1
SLES 15 SP6 nodejs22 22.23.0-150600.13.18.1 SUSE-SU-2026:2647-1
SLES 15 SP5 nodejs18 18.20.8-150400.9.39.1 SUSE-SU-2026:4261-1
SLES 15 SP5 nodejs20 20.20.2-150500.11.30.1 SUSE-SU-2026:3930-1
SLES 15 SP4 nodejs16 16.20.2-150400.3.42.1 SUSE-SU-2026:4355-1
SLES 15 SP4 nodejs18 18.20.8-150400.9.39.1 SUSE-SU-2026:4261-1
SLES 12 SP5 nodejs18 18.20.8-8.44.1 SUSE-SU-2026:4248-1
Show 7 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 nodejs22 22.23.0-160000.1.1 SUSE-SU-2026:22368-1
SLES for SAP 16.0 nodejs24 24.18.0-160000.1.1 SUSE-SU-2026:22565-1
SLES for SAP 15 SP6 nodejs20 20.20.2-150600.3.21.1 SUSE-SU-2026:3929-1
SLES for SAP 15 SP6 nodejs22 22.23.0-150600.13.18.1 SUSE-SU-2026:2647-1
SLES for SAP 15 SP5 nodejs18 18.20.8-150400.9.39.1 SUSE-SU-2026:4261-1
SLES for SAP 15 SP5 nodejs20 20.20.2-150500.11.30.1 SUSE-SU-2026:3930-1
SLES for SAP 15 SP4 nodejs16 16.20.2-150400.3.42.1 SUSE-SU-2026:4355-1
SLES for SAP 15 SP4 nodejs18 18.20.8-150400.9.39.1 SUSE-SU-2026:4261-1
SLES 16.0 nodejs22 22.23.0-160000.1.1 SUSE-SU-2026:22368-1
SLES 16.0 nodejs24 24.18.0-160000.1.1 SUSE-SU-2026:22565-1
SLE HPC 15 SP5 nodejs18 18.20.8-150400.9.39.1 SUSE-SU-2026:4261-1
SLE HPC 15 SP5 nodejs20 20.20.2-150500.11.30.1 SUSE-SU-2026:3930-1
SLE HPC 15 SP4 nodejs16 16.20.2-150400.3.42.1 SUSE-SU-2026:4355-1
SLE HPC 15 SP4 nodejs18 18.20.8-150400.9.39.1 SUSE-SU-2026:4261-1
ReleasePackageFixed inAdvisory
openSUSE Tumbleweed nodejs24 24.17.0-1.1 openSUSE-SU-2026:11121-1
openSUSE Leap 16.0 nodejs22 22.23.0-160000.1.1 openSUSE-SU-2026:21058-1
openSUSE Leap 16.0 nodejs24 24.18.0-160000.1.1 openSUSE-SU-2026:21236-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 nodejs22 +4 1:22.23.1-1.amzn2023.0.1 ALAS2023-2026-1921
Amazon Linux 2023 nodejs22-npm 1:10.9.8-1.22.23.1.1.amzn2023.0.1 ALAS2023-2026-1921
Amazon Linux 2023 nodejs24 +4 1:24.18.0-1.amzn2023.0.1 ALAS2023-2026-1920
Amazon Linux 2023 nodejs24-npm 1:11.16.0-1.24.18.0.1.amzn2023.0.1 ALAS2023-2026-1920
Amazon Linux 2023 v8-12.4-devel 3:12.4.254.21-1.22.23.1.1.amzn2023.0.1 ALAS2023-2026-1921
Amazon Linux 2023 v8-13.6-devel 3:13.6.233.17-1.24.18.0.1.amzn2023.0.1 ALAS2023-2026-1920

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 nodejs 24.18.1-1 —

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 10 nodejs +4 1:22.23.1-2.el10_2 ELSA-2026-35842
Oracle Linux 10 nodejs-npm 1:10.9.8-1.22.23.1.2.el10_2 ELSA-2026-35842
Oracle Linux 10 nodejs24 +4 1:24.18.0-1.0.1.el10_2 ELSA-2026-35841
Oracle Linux 10 nodejs24-npm 1:11.16.0-1.24.18.0.1.0.1.el10_2 ELSA-2026-35841
Oracle Linux 9 nodejs +4 1:22.23.1-1.module+el9.8.0+90947+d3e8e647 ELSA-2026-35892, ELSA-2026-35891
Oracle Linux 9 nodejs-nodemon 3.0.1-1.module+el9.8.0+90947+d3e8e647 ELSA-2026-35892, ELSA-2026-35891
Oracle Linux 9 nodejs-packaging +1 2021.06-6.module+el9.8.0+90946+13dc792a ELSA-2026-35892, ELSA-2026-35891
Oracle Linux 9 npm 1:10.9.8-1.22.23.1.1.module+el9.8.0+90947+d3e8e647 ELSA-2026-35892, ELSA-2026-35891
Oracle Linux 9 v8-12.4-devel 3:12.4.254.21-1.22.23.1.1.module+el9.8.0+90947+d3e8e647 ELSA-2026-35892
Oracle Linux 9 v8-13.6-devel 3:13.6.233.17-1.24.18.0.1.module+el9.8.0+90946+13dc792a ELSA-2026-35891
Oracle Linux 8 nodejs +4 1:22.23.1-1.module+el8.10.0+90968+e271b286 ELSA-2026-41947, ELSA-2026-39868
Oracle Linux 8 nodejs-nodemon 3.0.1-1.module+el8.10.0+90968+e271b286 ELSA-2026-41947, ELSA-2026-39868
Oracle Linux 8 nodejs-packaging +1 2021.06-4.module+el8.10.0+90968+e271b286 ELSA-2026-41947, ELSA-2026-39868
Oracle Linux 8 npm 1:10.9.8-1.22.23.1.1.module+el8.10.0+90968+e271b286 ELSA-2026-41947, ELSA-2026-39868
Oracle Linux 8 v8-12.4-devel 3:12.4.254.21-1.22.23.1.1.module+el8.10.0+90968+e271b286 ELSA-2026-41947
Oracle Linux 8 v8-13.6-devel 3:13.6.233.17-1.24.18.0.1.module+el8.10.0+90961+a86f8457 ELSA-2026-39868

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling code-server 4.125.0-r2 —
Wolfi rolling node-gyp 13.0.0-r1 —
Wolfi rolling npm 11.17.0-r1 —
Wolfi rolling prism 5.15.11-r3 —
Wolfi rolling renovate 43.247.0-r0 —
Wolfi rolling saf 1.6.0-r2 —
Wolfi rolling vitess-24 24.0.2-r1 —
Wolfi rolling vitess-24-compat 24.0.3-r7 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm undici < 6.27.0 6.27.0 GHSA-g8m3-5g58-fq7m
npm undici >= 7.0.0, < 7.28.0 7.28.0 GHSA-g8m3-5g58-fq7m
npm undici >= 8.0.0, < 8.5.0 8.5.0 GHSA-g8m3-5g58-fq7m

Advisories 43

References