{"id":"CVE-2026-86205","aliases":["GHSA-fp4x-ggrf-wmc6"],"url":"https://o3.security/vulnerability/CVE-2026-86205","summary":"h3 before 2.0.1-rc.18 Open Redirect via redirectBack()","details":"h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack() utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a Location header interpreted by browsers as a protocol-relative redirect to an external domain.","published":"2026-09-06T12:00:25.530Z","modified":"2026-09-10T03:30:21.961594181Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"h3","fixedVersion":"2.0.1-rc.18"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86205.json"},{"type":"ADVISORY","url":"https://github.com/h3js/h3/security/advisories/GHSA-fp4x-ggrf-wmc6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-86205"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-open-redirect-via-redirectback"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-10T03:30:21.961594181Z"}}