CVE-2026-86250

HIGHCVSS 7.5

Description

h3 versions before 2.0.1-rc.18 fail to validate the chunk count parsed from user-controlled cookie values in setChunkedCookie() and deleteChunkedCookie() functions. Attackers can send a crafted cookie header with an extremely large chunk count to trigger an O(n²) cleanup loop that hangs the server process.

Timeline

Published:September 6th, 2026 12:17 PM

Last modified:September 6th, 2026 12:17 PM

CVSS Scoring

CVSS v3: 7.5 (HIGH)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weaknesses (CWE)

CWE-400

References & Reports

Advisories, patches, and third-party reports

https://github.com/h3js/h3/security/advisories/GHSA-q5pr-72pq-83v3
https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-denial-of-service-via-unbounded-chunked-cookie

Source: NIST NVD · Data may lag official sources by up to one minute