{"id":"CVE-2026-86351","summary":"MISP User Homepage Validation Allows Authenticated Open Redirect via Protocol-Relative URL","details":"Affected versions of MISP validate the user-configurable homepage by checking only whether the supplied path begins with /. That check is insufficient because protocol-relative URLs such as //attacker.example also begin with / but resolve to an external origin in browsers.\n\n\nThe vulnerable homepage value can be stored as a user setting and later used by the post-login routing logic. The commit explicitly identifies //attacker.example as a payload that passed validation and was emitted to the Location header after login.\n\nThe fix introduces a shared InternalRedirectValidator that rejects URLs containing a host, scheme, userinfo, unsafe leading // or /\\, malformed URLs, and control characters. It also revalidates homepage settings on read so legacy or internally written unsafe values cannot bypass the new storage-time validation.\n\nVersion affected: ≤2.5.45","modified":"2026-09-10T03:31:05.389492034Z","published":"2026-09-07T09:59:34.850Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86351.json","cna_assigner":"CIRCL","cwe_ids":["CWE-20","CWE-601"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86351.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-86351"},{"type":"FIX","url":"https://github.com/MISP/MISP/commit/bd454f65a"},{"type":"PACKAGE","url":"https://github.com/MISP/MISP"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/misp/misp","events":[{"introduced":"0"},{"fixed":"bd454f65a"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"0"},{"last_affected":"2.5.45"}]}}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-86351.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N"}]}