Description
undici bundles a WebSocket client whose permessage-deflate size-limit cleanup removes all listeners from the internal zlib inflate stream, including its error listener, while that stream can still emit. When a remote peer sends a compressed payload that crosses the built-in 128 MiB decompressed-payload limit and then contains a malformed DEFLATE byte, the inflate stream emits a data error with no listener attached, which Node.js treats as a fatal unhandled error and terminates the entire process. Exploitation is remote and unauthenticated, requires no application mistake, and is asymmetric, since roughly 130 KB on the wire expands past the limit and crashes the process, and reconnecting can repeat the crash. This affects undici versions from 6.25.0 up to 6.28.1, from 7.28.0 up to 7.29.1, and from 8.1.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.
Affected products
nodejs: undici
References2
- cna.openjsf.org/security-advisories.html Vendor Advisory
- github.com/nodejs/undici/security/advisories/GHSA-3wwx-pv8p-q78v Vendor Advisory
Metrics
- CVSS 3.1
-
5.9
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 0% percentile: 36 · as of 7 November 2026
- CWE
- CWE-248
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