{"id":"CVE-2026-86205","state":"PUBLISHED","title":"h3 before 2.0.1-rc.18 Open Redirect via redirectBack()","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.","publishedAt":"2026-09-06T12:00:25.530Z","updatedAt":"2026-09-08T13:28:55.791Z","severity":{"score":5.3,"label":"Medium","version":"4.0","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","source":"VulnCheck"},"assigner":"VulnCheck","products":["h3js h3"],"affected":[{"vendor":"h3js","product":"h3","packageURL":"pkg:npm/h3","defaultStatus":"unaffected","versions":[{"version":"2.0.1-rc.17","status":"affected","lessThan":"2.0.1-rc.18","versionType":"semver"},{"version":"2.0.1-rc.18","status":"unaffected","versionType":"semver"}]}],"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"],"weaknesses":["CWE-601"],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/86xxx/CVE-2026-86205.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-86205","state":"PUBLISHED","datePublished":"2026-09-06T12:00:25.530Z","dateUpdated":"2026-09-08T13:28:55.791Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-09-05T11:52:36.822Z"},"containers":{"cna":{"title":"h3 before 2.0.1-rc.18 Open Redirect via redirectBack()","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"h3js","product":"h3","packageURL":"pkg:npm/h3","defaultStatus":"unaffected","versions":[{"version":"2.0.1-rc.17","status":"affected","lessThan":"2.0.1-rc.18","versionType":"semver"},{"version":"2.0.1-rc.18","status":"unaffected","versionType":"semver"}]}],"references":[{"url":"https://github.com/h3js/h3/security/advisories/GHSA-fp4x-ggrf-wmc6","tags":["vendor-advisory"],"name":"GitHub Security Advisory (GHSA-fp4x-ggrf-wmc6)"},{"url":"https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-open-redirect-via-redirectback","name":"VulnCheck Advisory: h3 before 2.0.1-rc.18 Open Redirect via redirectBack()","tags":["third-party-advisory"]}],"metrics":[{"format":"CVSS","cvssV4_0":{"version":"4.0","vectorString":"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","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM"}},{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE","baseScore":5.4,"baseSeverity":"MEDIUM"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-601","lang":"en","description":"URL Redirection to Untrusted Site ('Open Redirect')","type":"CWE"}]}],"providerMetadata":{"shortName":"VulnCheck","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateUpdated":"2026-09-06T12:00:25.530Z"},"datePublic":"2026-03-21T00:00:00.000Z","credits":[{"lang":"en","value":"offset","type":"reporter"}],"x_generator":{"engine":"vulncheck-endgame"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/h3js/h3/security/advisories/GHSA-fp4x-ggrf-wmc6","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-08T13:28:03.688110Z","id":"CVE-2026-86205","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-08T13:28:55.791Z"}}]}}}