{"id":"CVE-2026-86250","revision":"26e8b4bd6ccc4d94862829119e595b39","records":[{"revision":"26e8b4bd6ccc4d94862829119e595b39","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-86250","aliases":[],"title":"h3 before 2.0.1-rc.18 Denial of Service via Unbounded Chunked Cookie","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.","state":0,"publishedAt":"2026-09-06T12:00:26.211+00:00","modifiedAt":"2026-09-18T17:23:10.52+00:00","affected":[{"ecosystem":"Vendor product","name":"h3","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"h3js\",\n                    \"product\": \"h3\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"packageURL\": \"pkg:npm/h3\",\n                    \"versions\": [\n                        {\n                            \"version\": \"2.0.0-beta.4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\",\n                            \"lessThan\": \"2.0.1-rc.18\"\n                        },\n                        {\n                            \"version\": \"2.0.1-rc.18\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","score":8.7,"severity":"HIGH"},{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["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"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-86250","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-86250","identifiers":["CVE-2026-86250"]},"retained":false,"historicalAffected":[]}],"coverage":[]}