undici vulnerable to Denial of Service via unhandled exception in the decompress interceptor
CVE-2026-87029
Impact undici's decompress interceptor forwards decompressed response data to the downstream handler from zlib stream event callbacks without catching exceptions those callbacks may throw. undici's engine converts a synchronous throw from a downstream handler into a per-request failure, but that protection is not in place when the throw happens asynchronously from a zlib callback. As a result, a downstream handler that throws by design, for example the built-in dump interceptor which throws when a response exceeds its maxSize, escapes as an uncaught exception and terminates the Node.js process. A malicious or compromised HTTP server can crash any client that composes the decompress interceptor with dump (or another response handler that throws), by returning a small compressed body that decompresses to more than the configured limit. The compressed bytes on the wire are tiny, so only the decompressed size matters. If the application keeps the process alive with a global uncaught-exception handler, the affected request instead hangs until the body timeout. Patches Upgrade to undici 7.30.1 or 8.12.2. Workarounds Avoid composing the decompress interceptor with a response handler that…
Assessment
- CVSS
- 5.9 (v3.1)
- Severity
- Medium
- EPSS
- 0.0026% 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
- 27 October 2026
- Last updated
- 27 October 2026
- Affected
- npm · undici
- Weakness
- CWE-248
CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
At the source
References
- https://github.com/nodejs/undici/security/advisories/GHSA-55wc-3pg8-jfw6
- https://nvd.nist.gov/vuln/detail/CVE-2026-87029
- https://github.com/nodejs/undici/commit/63cba7712ca012b2603c6aeeb4c72d8692332cd0
- https://github.com/nodejs/undici/commit/f851f315db1f2acce0ea668f88d9d0fa61c8420c
- https://cna.openjsf.org/security-advisories.html
- 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-55wc-3pg8-jfw6
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