CVE-2026-86250h3 before 2.0.1-rc.18 Denial of Service via Unbounded Chunked Cookie
Updated under an hour ago ()
Does this affect you?
It affects h3js h3. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-400
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Awaiting Analysis
- Record last updated
- Sep 18, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
h3js h3 h3js:h3 (from the name) | from 2.0.0-beta.4 before 2.0.1-rc.18; 2.0.1-rc.18 not affected | CNA record |
References
- https://github.com/h3js/h3/security/advisories/GHSA-q5pr-72pq-83v3vendor-advisory
- https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-denial-of-service-via-unbounded-chunked-cookiethird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.