{"id":"CVE-2026-86250","title":"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","summary":"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…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-400","CWE-606"],"vendor":"Red Hat","product":"Red Hat OpenShift AI (RHOAI)","affected":["openshift_ai_rhoai"],"published":"2026-09-06","updated":"2026-09-18","sourceUpdated":"2026-09-18T18:17:18.657","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-86250","references":[{"url":"https://github.com/h3js/h3/security/advisories/GHSA-q5pr-72pq-83v3","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-denial-of-service-via-unbounded-chunked-cookie","label":"disclosure@vulncheck.com"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-86250.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-86250"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2529162"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-86250"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-86250"}],"tags":["nvd","csaf","vex","red-hat","cve.org"],"epss":0.00278,"epssPercentile":0.20526,"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-09-18T17:07:52.002310Z"},"ingestedAt":"2026-09-07T03:04:07.576Z","slug":"CVE-2026-86250","body":"## Overview\n\nh3 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Important · affected: Red Hat OpenShift AI (RHOAI) · no fix planned: Red Hat OpenShift AI (RHOAI) · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-86250.json)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}