CVE-2026-84933

Summary

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 Software

VendorProductVersion RangeStatus
undiciundici7.0.0 < 7.29.1affected
undiciundici7.29.1unaffected
undiciundici8.0.0 < 8.10.2affected
undiciundici8.10.2unaffected

Weaknesses

  • CWE-200: CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-524: CWE-524: Use of Cache Containing Sensitive Information

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References