Vulnerability Description
undici's retry handler can leave an already-exposed response body pending forever. When a server returns a successful response that declares a Content-Length, sends only part of the body, and closes the connection, the retry handler retries the request. If the retry returns a non-retryable status such as 400, the handler forwards that new response downstream and replaces its internal response stream, but the original response body that the application still holds is never ended or destroyed. As a result calls that read that body never settle, and the configured body timeout does not fire because its timer is tied to the connection parser rather than the orphaned body. An attacker-controlled server can trigger this with two short responses without keeping a connection open, and repeated requests accumulate pending promises and streams that can exhaust application concurrency or memory. This affects undici versions from 7.11.0 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Nodejs | Undici | >= 7.11.0, < 7.29.1 |
Related Weaknesses (CWE)
References
- https://cna.openjsf.org/security-advisories.htmlVendor Advisory
- https://github.com/nodejs/undici/security/advisories/GHSA-pmjh-fq2x-6v4xMitigationVendor Advisory
FAQ
What is CVE-2026-18149?
CVE-2026-18149 is a vulnerability with a CVSS score of 5.9 (MEDIUM). undici's retry handler can leave an already-exposed response body pending forever. When a server returns a successful response that declares a Content-Length, sends only part of the body, and closes t...
How severe is CVE-2026-18149?
CVE-2026-18149 has been rated MEDIUM with a CVSS base score of 5.9/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-18149?
Check the references section above for vendor advisories and patch information. Affected products include: Nodejs Undici.