EUVD-2026-37758Published

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

Exploitation and risk

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cve-program · CVE-2026-11525

Published

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.

Source published: 17 Jun 2026 17:31:03 UTC
Source modified: 17 Jun 2026 17:54:22 UTC
Saved here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

euvd · EUVD-2026-37758

Published

Additional publisher context

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: Jun 17, 2026, 5:31:03 PM

dateUpdated: Jun 17, 2026, 5:54:22 PM

21 related source bulletins · separate from aliases

SUSE-SU-2026:4248-1: Security update for nodejs18

CVE-2025-22150 · CVE-2025-23166 · CVE-2025-23167 · CVE-2025-55131 · CVE-2025-59465 · CVE-2025-59466 · CVE-2025-62408 · CVE-2026-11525 · CVE-2026-12151 · CVE-2026-15157 · CVE-2026-16728 · CVE-2026-16729 · CVE-2026-21637 · CVE-2026-21710 · CVE-2026-21713 · CVE-2026-21714 · CVE-2026-21717 · CVE-2026-22036 · CVE-2026-27135 · CVE-2026-48618 · CVE-2026-48619 · CVE-2026-48928 · CVE-2026-48930 · CVE-2026-48931 · CVE-2026-48933 · CVE-2026-48934 · CVE-2026-48935 · CVE-2026-48937 · CVE-2026-56846 · CVE-2026-56848 · CVE-2026-56850 · CVE-2026-58040 · CVE-2026-58042 · CVE-2026-58043 · CVE-2026-58044 · CVE-2026-58045 · CVE-2026-6733 · CVE-2026-9679

WID-SEC-W-2026-2618: IBM App Connect Enterprise: Mehrere Schwachstellen

CVE-2026-11525 · CVE-2026-12151 · CVE-2026-13676 · CVE-2026-53550 · CVE-2026-54285 · CVE-2026-59869 · CVE-2026-59877 · CVE-2026-6733 · CVE-2026-6734 · CVE-2026-9675 · CVE-2026-9678 · CVE-2026-9679 · CVE-2026-9697

RHSA-2026:38236: Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update

CVE-2026-5078 · CVE-2026-6733 · CVE-2026-6734 · CVE-2026-9678 · CVE-2026-9679 · CVE-2026-9697 · CVE-2026-11525 · CVE-2026-12151 · CVE-2026-53550 · CVE-2026-59869

RHSA-2026:39868: Red Hat Security Advisory: nodejs:24 security, bug fix, and enhancement update

CVE-2026-6733 · CVE-2026-6734 · CVE-2026-9678 · CVE-2026-9697 · CVE-2026-11525 · CVE-2026-12151 · CVE-2026-42338 · CVE-2026-48615 · CVE-2026-48617 · CVE-2026-48618 · CVE-2026-48619 · CVE-2026-48928 · CVE-2026-48930 · CVE-2026-48931 · CVE-2026-48933 · CVE-2026-48934 · CVE-2026-48935 · CVE-2026-48937

openSUSE-SU-2026:21236-1: Security update for nodejs24

CVE-2026-11525 · CVE-2026-12151 · CVE-2026-2581 · CVE-2026-27135 · CVE-2026-40170 · CVE-2026-42338 · CVE-2026-48615 · CVE-2026-48617 · CVE-2026-48618 · CVE-2026-48619 · CVE-2026-48928 · CVE-2026-48930 · CVE-2026-48931 · CVE-2026-48933 · CVE-2026-48934 · CVE-2026-48935 · CVE-2026-48937 · CVE-2026-6733 · CVE-2026-9496 · CVE-2026-9678 · CVE-2026-9679

RHSA-2026:35892: Red Hat Security Advisory: nodejs:22 security, bug fix, and enhancement update

CVE-2026-6733 · CVE-2026-9678 · CVE-2026-11525 · CVE-2026-12151 · CVE-2026-42338 · CVE-2026-48615 · CVE-2026-48617 · CVE-2026-48618 · CVE-2026-48619 · CVE-2026-48928 · CVE-2026-48930 · CVE-2026-48931 · CVE-2026-48933 · CVE-2026-48934 · CVE-2026-48935 · CVE-2026-48937

RHSA-2026:35891: Red Hat Security Advisory: nodejs:24 security, bug fix, and enhancement update

openSUSE-SU-2026:21058-1: Security update for nodejs22

CVE-2026-11525 · CVE-2026-12151 · CVE-2026-21637 · CVE-2026-21710 · CVE-2026-21713 · CVE-2026-21714 · CVE-2026-21715 · CVE-2026-21716 · CVE-2026-21717 · CVE-2026-27135 · CVE-2026-40170 · CVE-2026-42338 · CVE-2026-48615 · CVE-2026-48617 · CVE-2026-48618 · CVE-2026-48619 · CVE-2026-48928 · CVE-2026-48930 · CVE-2026-48931 · CVE-2026-48933 · CVE-2026-48934 · CVE-2026-48935 · CVE-2026-48937 · CVE-2026-6733 · CVE-2026-9496 · CVE-2026-9679

RHSA-2026:41947: Red Hat Security Advisory: nodejs:22 security, bug fix, and enhancement update

SUSE-SU-2026:22368-1: Security update for nodejs22

RHSA-2026:35841: Red Hat Security Advisory: nodejs24 security, bug fix, and enhancement update

SUSE-SU-2026:2647-1: Security update for nodejs22

CVE-2026-11525 · CVE-2026-12151 · CVE-2026-27135 · CVE-2026-40170 · CVE-2026-42338 · CVE-2026-48615 · CVE-2026-48617 · CVE-2026-48618 · CVE-2026-48619 · CVE-2026-48928 · CVE-2026-48930 · CVE-2026-48931 · CVE-2026-48933 · CVE-2026-48934 · CVE-2026-48935 · CVE-2026-48937 · CVE-2026-6733 · CVE-2026-9496 · CVE-2026-9679

msrc_CVE-2026-11525: undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching

CVE-2026-11525

SUSE-SU-2026:3929-1: Security update for nodejs20

CVE-2025-22150 · CVE-2026-11525 · CVE-2026-12151 · CVE-2026-16728 · CVE-2026-16729 · CVE-2026-22036 · CVE-2026-27135 · CVE-2026-40170 · CVE-2026-42338 · CVE-2026-48615 · CVE-2026-48617 · CVE-2026-48618 · CVE-2026-48619 · CVE-2026-48928 · CVE-2026-48930 · CVE-2026-48931 · CVE-2026-48933 · CVE-2026-48934 · CVE-2026-48935 · CVE-2026-48937 · CVE-2026-54272 · CVE-2026-56846 · CVE-2026-56847 · CVE-2026-56848 · CVE-2026-56850 · CVE-2026-58039 · CVE-2026-58040 · CVE-2026-58042 · CVE-2026-58043 · CVE-2026-58044 · CVE-2026-58045 · CVE-2026-6733 · CVE-2026-69192 · CVE-2026-9496 · CVE-2026-9679

RHSA-2026:56431: Red Hat Security Advisory: Red Hat OpenShift Data Foundation 4.18.27 security, enhancement & bug fix update

CVE-2025-61726 · CVE-2025-61729 · CVE-2025-64718 · CVE-2025-68470 · CVE-2026-1525 · CVE-2026-1526 · CVE-2026-1527 · CVE-2026-2229 · CVE-2026-6321 · CVE-2026-6322 · CVE-2026-6733 · CVE-2026-6734 · CVE-2026-9358 · CVE-2026-9679 · CVE-2026-9697 · CVE-2026-11525 · CVE-2026-12143 · CVE-2026-12151 · CVE-2026-13149 · CVE-2026-13676 · CVE-2026-22036 · CVE-2026-25645 · CVE-2026-33186 · CVE-2026-33349 · CVE-2026-33671 · CVE-2026-33672 · CVE-2026-33750 · CVE-2026-34043 · CVE-2026-34986 · CVE-2026-35469 · CVE-2026-39821 · CVE-2026-40181 · CVE-2026-41305 · CVE-2026-41650 · CVE-2026-41907 · CVE-2026-42342 · CVE-2026-45409 · CVE-2026-45736 · CVE-2026-48779 · CVE-2026-48801 · CVE-2026-53550 · CVE-2026-59869

SUSE-SU-2026:22565-1: Security update for nodejs24

openSUSE-SU-2026:11121-1: corepack24-24.17.0-1.1 on GA media

SUSE-SU-2026:3930-1: Security update for nodejs20

RHSA-2026:45783: Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

CVE-2026-11525 · CVE-2026-48617

WID-SEC-W-2026-2919: IBM App Connect Enterprise: Mehrere Schwachstellen

CVE-2024-34459 · CVE-2025-10911 · CVE-2025-13151 · CVE-2025-5278 · CVE-2025-6170 · CVE-2025-66293 · CVE-2026-11525 · CVE-2026-12151 · CVE-2026-15308 · CVE-2026-15709 · CVE-2026-15711 · CVE-2026-15713 · CVE-2026-15714 · CVE-2026-31790 · CVE-2026-33416 · CVE-2026-33636 · CVE-2026-34180 · CVE-2026-34181 · CVE-2026-34182 · CVE-2026-34183 · CVE-2026-42338 · CVE-2026-42764 · CVE-2026-42766 · CVE-2026-42767 · CVE-2026-42768 · CVE-2026-42769 · CVE-2026-42770 · CVE-2026-42771 · CVE-2026-45445 · CVE-2026-45446 · CVE-2026-45447 · CVE-2026-47058 · CVE-2026-48615 · CVE-2026-48618 · CVE-2026-48619 · CVE-2026-48864 · CVE-2026-48928 · CVE-2026-48930 · CVE-2026-48933 · CVE-2026-48934 · CVE-2026-48935 · CVE-2026-54369 · CVE-2026-54370 · CVE-2026-5450 · CVE-2026-58016 · CVE-2026-65698 · CVE-2026-6733 · CVE-2026-6734 · CVE-2026-7383 · CVE-2026-8643 · CVE-2026-9076 · CVE-2026-9678 · CVE-2026-9697

RHSA-2026:35842: Red Hat Security Advisory: nodejs22 security, bug fix, and enhancement update

Source published: Jun 17, 2026, 5:31:03 PM (timezone not stated)
Source modified: Jun 17, 2026, 5:54:22 PM (timezone not stated)
Saved here: 15 Nov 2026 10:11:43 UTC
Source terms: ENISA EUVD · source terms and attribution apply

Original source record · Cite this exact observation · Complete original publisher JSON

Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

EUVD CVSS 3.1 · 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

nvd · CVE-2026-11525

Published

Additional publisher context

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Analyzed

Weakness classifications: CWE-183

Original publisher date fields

published: 2026-06-17T18:17:35.097

lastModified: 2026-06-25T17:46:21.653

1 source CPE criteria · context only

cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*

The original JSON retains the logical configuration operators, exclusions and version bounds.

Source published: 17 Jun 2026 18:17:35 UTC
Source modified: 25 Jun 2026 17:46:21 UTC
Saved here: 25 Oct 2026 05:17:18 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary · 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

osv · GHSA-g8m3-5g58-fq7m

Published

## 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: - `SameSite=NoneOfYourBusiness` is parsed as `None`, the most permissive setting. - `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 v6.27.0, 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.

Source published: 19 Jun 2026 14:34:46 UTC
Source modified: 10 Sep 2026 03:51:08 UTC
Saved here: 24 Oct 2026 13:17:17 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Publisher rating · LOW