GHSA-q5pr-72pq-83v3: H3: Unbounded Chunked Cookie Count in Session Cleanup Loop may Lead to Denial of Service
(updated )
The setChunkedCookie() and deleteChunkedCookie() functions in h3 trust the chunk count parsed from a user-controlled cookie value (__chunked__N) without any upper bound validation. An unauthenticated attacker can send a single request with a crafted cookie header (e.g., Cookie: h3=__chunked__999999) to any endpoint using sessions, causing the server to enter an O(n²) loop that hangs the process.
References
- github.com/advisories/GHSA-q5pr-72pq-83v3
- github.com/h3js/h3/commit/399257cb406fbeda313d88c1e288a15124fc82af
- github.com/h3js/h3/releases/tag/v2.0.1-rc.18
- github.com/h3js/h3/security/advisories/GHSA-q5pr-72pq-83v3
- nvd.nist.gov/vuln/detail/CVE-2026-86250
- www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-denial-of-service-via-unbounded-chunked-cookie
Code Behaviors & Features
Detect and mitigate GHSA-q5pr-72pq-83v3 with GitLab Dependency Scanning
Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →