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.

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Fixes

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History

Fri, 04 Sep 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 04 Sep 2026 17:15:00 +0000

Type Values Removed Values Added
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.
Title undici vulnerable to cross-user cookie disclosure via Set-Cookie caching in shared caches
Weaknesses CWE-200
CWE-524
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-09-04T18:34:14.407Z

Reserved: 2026-09-02T16:20:41.850Z

Link: CVE-2026-84933

cve-icon Vulnrichment

Updated: 2026-09-04T18:34:10.888Z

cve-icon NVD

Status : Received

Published: 2026-09-04T17:17:01.973

Modified: 2026-09-04T19:17:30.163

Link: CVE-2026-84933

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses