CVE Feed
5.9 Medium

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

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