undici vulnerable to Denial of Service via unhandled error on excessive content-encodings
CVE-2026-109869
Impact undici's fetch() crashes the Node.js process when a malicious server returns a response with more than five content codings and closes the connection before sending the body. undici rejects such responses (a content-encoding limit), but it created the internal response stream before that check and returned without attaching an error listener or aborting the request. The early close then surfaces a content-length mismatch on that orphaned internal stream, which Node.js treats as an unhandled error and terminates the process. A remote, unauthenticated server can trigger this with a single response, even when the application correctly catches the fetch() rejection. undici 6.x, 7.x, and 8.x are affected. Patches Upgrade to 6.29.1, 7.30.1, or 8.12.2. undici now validates the content-encoding chain before creating the internal body stream and aborts the response when the limit is exceeded, so no error can surface on an orphaned stream. Workarounds None.
Assessment
- CVSS
- 7.5 (v3.1)
- Severity
- High
- EPSS
- 0.00344% chance of exploitation in the next 30 days
- Known exploited
- Not listed in CISA KEV
- Exploit availability
- Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
- Published
- 23 October 2026
- Last updated
- 23 October 2026
- Affected
- npm · undici
- Weakness
- CWE-248, CWE-459
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
At the source
References
- https://github.com/nodejs/undici/security/advisories/GHSA-xjj6-f33q-929c
- https://nvd.nist.gov/vuln/detail/CVE-2026-109869
- https://github.com/nodejs/undici/commit/07ded4941b1e72afec862958c3b8ddf468f3b429
- https://github.com/nodejs/undici/commit/1325a87dfb3492f8e87e6b0a84b3bda4e82e3436
- https://github.com/nodejs/undici/commit/b5084c7dc239172d75c336b1cd51ddac023938a5
- https://cna.openjsf.org/security-advisories.html
- https://github.com/nodejs/undici/releases/tag/v6.29.1
- https://github.com/nodejs/undici/releases/tag/v7.30.1
- https://github.com/nodejs/undici/releases/tag/v8.12.2
- https://github.com/advisories/GHSA-xjj6-f33q-929c
Query this programmatically
Agents can read this through the MCP endpoint, or over HTTP:
curl https://cve.zerocrew.in/api/cve/CVE-2026-109869