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TI-2026-09954 Aliases CVE-2026-11525GHSA-g8m3-5g58-fq7m

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

Priority LOW 17CWE-183Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
None · Low · None
Fix status
Partial Red Hat: 5 fixed, 12 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00238 14th percentileScored 2026-11-07
Fix Partial undici (undici): 6.26.0, 7.28.0, 8.5.0undici (npm): 6.27.0, 7.28.0, 8.5.0Red Hat: 9 advisoriesRed Hat: 5 fixed, 12 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
NodeJSundicibefore 6.26.0; 7.0.0 to before 7.28.0; 8.0.0 to before 8.5.06.26.0, 7.28.0, 8.5.0Patch availableCNA
—undici (npm)before 6.27.06.27.0Patch availableGHSA-g8m3-5g58-fq7m
—undici (npm)7.0.0 to before 7.28.07.28.0Patch availableGHSA-g8m3-5g58-fq7m
—undici (npm)8.0.0 to before 8.5.08.5.0Patch availableGHSA-g8m3-5g58-fq7m
  • undici VendorNodeJS Affected before 6.26.0; 7.0.0 to before 7.28.0; 8.0.0 to before 8.5.0 Fixed in 6.26.0, 7.28.0, 8.5.0 Patch available CNA
  • undici (npm) Vendor— Affected before 6.27.0 Fixed in 6.27.0 Patch available GHSA-g8m3-5g58-fq7m
  • undici (npm) Vendor— Affected 7.0.0 to before 7.28.0 Fixed in 7.28.0 Patch available GHSA-g8m3-5g58-fq7m
  • undici (npm) Vendor— Affected 8.0.0 to before 8.5.0 Fixed in 8.5.0 Patch available GHSA-g8m3-5g58-fq7m

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*before 6.27.0; 7.0.0 to before 7.28.0; 8.0.0 to before 8.5.0VulnerableNodeJS
  • cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:* Versions before 6.27.0; 7.0.0 to before 7.28.0; 8.0.0 to before 8.5.0 Vulnerable ·NodeJS

Remediation

  • Fix · CNA undici (undici) Fixed in 6.26.0, 7.28.0, 8.5.0
  • Fix · GHSA-g8m3-5g58-fq7m undici (npm) Fixed in 6.27.0 Advisory →
  • Fix · GHSA-g8m3-5g58-fq7m undici (npm) Fixed in 7.28.0 Advisory →
  • Fix · GHSA-g8m3-5g58-fq7m undici (npm) Fixed in 8.5.0 Advisory →

Red Hat 9 advisories

  • RHSA-2026:56431 Released 2026-08-18 · Red Hat rating Important
    Red Hat OpenShift Data Foundation 4.18.27 security, enhancement & bug fix update
    • Red Hat Openshift Data Foundation 4.18 registry.redhat.io/odf4/cephcsi-rhel9, registry.redhat.io/odf4/cephcsi-rhel9-operator, registry.redhat.io/odf4/mcg-core-rhel9 +16
  • RHSA-2026:45783 Released 2026-07-25 · Red Hat rating Low
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images nodejs26-1:26.5.0-1.5.hum1@aarch64, nodejs26-1:26.5.0-1.5.hum1@src, nodejs26-1:26.5.0-1.5.hum1@x86_64 +14
  • RHSA-2026:41947 Released 2026-07-20 · Red Hat rating Important
    nodejs:22 security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 8) nodejs-1:22.23.1-1.module+el8.10.0+24500+8eb51621.aarch64::nodejs:22, nodejs-1:22.23.1-1.module+el8.10.0+24500+8eb51621.ppc64le::nodejs:22, nodejs-1:22.23.1-1.module+el8.10.0+24500+8eb51621.s390x::nodejs:22 +28
Show 6 more Red Hat advisories
  • RHSA-2026:39868 Released 2026-07-15 · Red Hat rating Important
    nodejs:24 security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 8) nodejs-1:24.18.0-1.module+el8.10.0+24481+7a71fac8.aarch64::nodejs:24, nodejs-1:24.18.0-1.module+el8.10.0+24481+7a71fac8.ppc64le::nodejs:24, nodejs-1:24.18.0-1.module+el8.10.0+24481+7a71fac8.s390x::nodejs:24 +25
  • RHSA-2026:38236 Released 2026-07-11 · Red Hat rating Important
    Red Hat Hardened Images RPMs Security Update
    • Red Hat Hardened Images nodejs24-1:24.18.0-0.3.hum1@aarch64, nodejs24-1:24.18.0-0.3.hum1@src, nodejs24-1:24.18.0-0.3.hum1@x86_64 +16
  • RHSA-2026:35892 Released 2026-07-06 · Red Hat rating Important
    nodejs:22 security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 9) nodejs-1:22.23.1-1.module+el9.8.0+24457+996af7aa.aarch64::nodejs:22, nodejs-1:22.23.1-1.module+el9.8.0+24457+996af7aa.ppc64le::nodejs:22, nodejs-1:22.23.1-1.module+el9.8.0+24457+996af7aa.s390x::nodejs:22 +28
  • RHSA-2026:35891 Released 2026-07-06 · Red Hat rating Important
    nodejs:24 security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 9) nodejs-1:24.18.0-1.module+el9.8.0+24456+b244c3b4.aarch64::nodejs:24, nodejs-1:24.18.0-1.module+el9.8.0+24456+b244c3b4.ppc64le::nodejs:24, nodejs-1:24.18.0-1.module+el9.8.0+24456+b244c3b4.s390x::nodejs:24 +25
  • RHSA-2026:35842 Released 2026-07-06 · Red Hat rating Important
    nodejs22 security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 10) nodejs-1:22.23.1-2.el10_2, nodejs-devel-1:22.23.1-2.el10_2, nodejs-docs-1:22.23.1-2.el10_2 +4
  • RHSA-2026:35841 Released 2026-07-06 · Red Hat rating Important
    nodejs24 security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 10) nodejs24-1:24.18.0-1.el10_2, nodejs24-devel-1:24.18.0-1.el10_2, nodejs24-docs-1:24.18.0-1.el10_2 +3

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    undici 6.26.0, 7.28.0, 8.5.0

    4 records Highest priority Priority MEDIUM 1 MEDIUM, 3 LOW

    Other records, highest priority first

    • TI-2026-10459 undici WebSocket client vulnerable to denial of service via fragment count bypassPriority MEDIUM 40
    • TI-2026-08490 undici vulnerable to HTTP header injection via Set-Cookie percent-decodingPriority LOW 26
    • TI-2026-05899 undici vulnerable to HTTP response queue poisoning via keep-alive socket reusePriority LOW 17
    Show all 4 records →

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

ProductStatusPlan or fix
Cryostat 4AffectedNo fix yet: Fix deferred
OpenShift PipelinesAffectedNo fix yet: Fix deferred
Red Hat AMQ Broker 7AffectedNo fix yet: Fix deferred
Red Hat Build of Podman DesktopAffectedNo fix yet: Fix deferred
Red Hat Developer Hub 1AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Hardened ImagesAffectedNo fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 4AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 5AffectedNo fix yet: Fix deferred
Red Hat OpenShift Dev SpacesAffectedNo fix yet: Fix deferred
Self-service automation portal 2AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:35841, RHSA-2026:35842
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2026:39868, RHSA-2026:41947
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:35891, RHSA-2026:35892
Red Hat Hardened ImagesFixed RHSA-2026:38236, RHSA-2026:45783
Red Hat Openshift Data Foundation 4.18Fixed RHSA-2026:56431
Not affected: 2 products
  • Red Hat Hardened Images
  • Red Hat Openshift Data Foundation 4.18

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-11525
  2. 2026-10-03 Alias added: GHSA-g8m3-5g58-fq7m
  3. 2026-10-27 Affected versions changed · Red Hat
  4. 2026-11-06 Affected versions changed · Red Hat

References

Advisory 3

Other 1

  • TI-2026-01215 undici is vulnerable to Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') CVSS 3.1CRITICAL 9.8
  • TI-2022-16376 `undici.request` vulnerable to SSRF using absolute URL on `pathname` CVSS 3.1CRITICAL 9.8
  • TI-2023-09734 CRLF Injection in Nodejs ‘undici’ via host CVSS 3.1MEDIUM 6.5
  • TI-2022-13193 CRLF injection in request headers CVSS 3.1MEDIUM 6.5
  • TI-2022-16375 CRLF Injection in Nodejs ‘undici’ via Content-Type CVSS 3.1MEDIUM 5.3
  • TI-2022-13194 Uncleared cookies on cross-host/cross-origin redirect in undici CVSS 3.1MEDIUM 6.5
See all 51 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences