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VulnerabilityPublished

CVE-2026-109829: undici vulnerable to cache poisoning and cross-user disclosure via cross-origin redirects

Affects undiciSource GCVE Database

0

Not known to be exploited · CVSS 7.4 High : upgrade to 7.30.1 soon.

Data as of 27 Oct 2026, 20:28 UTC

CVSS 3.1 base score
7.4High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 7.30.1, 8.12.2
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade undici to 7.30.1; undici to 8.12.2.

Affected software

ProductAffectedFixed in
npmundiciAffected
  • >=7.0.0 <7.30.1
Fixed in
  • 7.30.1
npmundiciAffected
  • >=8.0.0 <8.12.2
Fixed in
  • 8.12.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade undici to version 7.30.1 or 8.12.2, where the vulnerability is fixed by verifying that the origin producing the response matches the cache key before storing it and by preserving cache-control policies across redirect hops. Alternatively, as a workaround, compose the interceptors as compose(cache(), redirect()), use per-origin dispatchers and cache stores, or disable shared caching on redirect-capable requests. These mitigations prevent cross-origin cache poisoning and data disclosure.

Description

undici versions 7.0.0 through before 7.30.1 and 8.0.0 through before 8.12.2 have a cache poisoning and cross-user data disclosure vulnerability when using an originless Agent with composed redirect and shared cache interceptors. The cache key is built from the original request URL before redirects change the origin, causing responses from redirected origins to be cached under the original URL. This allows an attacker controlling the redirect target to poison the cache or disclose private data to other users. The issue is fixed in versions 7.30.1 and 8.12.2 by verifying origin consistency before caching and preserving cache-control policies across redirects.

References

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