{"cve":"CVE-2026-86205","nvd":{"published":"2026-09-06T12:17:15.277","modified":"2026-09-08T20:00:18.870","status":"Awaiting Analysis","description":"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.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","score":5.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N","score":5.4},"cwes":["CWE-601"],"references":["https://github.com/h3js/h3/security/advisories/GHSA-fp4x-ggrf-wmc6","https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-open-redirect-via-redirectback","https://github.com/h3js/h3/security/advisories/GHSA-fp4x-ggrf-wmc6"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:52:03.409947763+00:00"},"epss":{"cve":"CVE-2026-86205","score":0.00271,"percentile":0.19364,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-fp4x-ggrf-wmc6","url":"https://osv.dev/vulnerability/GHSA-fp4x-ggrf-wmc6","summary":"H3 has an Open Redirect via Protocol-Relative Path in redirectBack() Referer Validation","modified":"2026-09-10T03:51:00.303376066Z","packages":[{"ecosystem":"npm","name":"h3","purl":"pkg:npm/h3","ranges":[">=2.0.1-rc.17 <2.0.1-rc.18"],"fixed":["2.0.1-rc.18"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}