{"id":"CVE-2026-86351","aliases":["EUVD-2026-72343","GHSA-7q84-h6g5-j34g"],"status":"published","title":"MISP User Homepage Validation Allows Authenticated Open Redirect via Protocol-Relative URL","description":"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","severity":{"version":"4.0","score":5.1,"vector":"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00259,"percentile":0.17694,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-20","CWE-601"],"published":"2026-09-07T09:59:34Z","modified":"2026-10-28T02:30:30Z","products":[{"vendor":"misp","product":"misp"},{"vendor":"misp-project","product":"misp"}],"references":[{"url":"https://github.com/MISP/MISP/commit/bd454f65a","tags":["patch","Patch","fix"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-86351","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-7q84-h6g5-j34g"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86351.json","tags":["advisory"]},{"url":"https://github.com/MISP/MISP","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-86351","title":"MISP User Homepage Validation Allows Authenticated Open Redirect via Protocol-Relative URL","description":"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","status":"published","published":"2026-09-07T09:59:34.85Z","modified":"2026-09-08T14:49:21.745Z","cvss":[{"version":"4.0","score":5.1,"vector":"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","level":"medium","assessor":"cna"}],"cwes":["CWE-601","CWE-20"],"updated_at":"2026-11-02T13:49:31.546614Z"}],"euvd":[{"id":"EUVD-2026-72343","description":"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","status":"published","published":"2026-09-07T09:59:34Z","modified":"2026-09-08T14:49:21Z","cvss":[{"version":"4.0","score":5.1,"vector":"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","level":"medium"}],"updated_at":"2026-11-02T17:28:29.426Z"}],"ghsa":[{"id":"GHSA-7q84-h6g5-j34g","title":"Affected versions of MISP validate the user-configurable homepage by checking only whether the...","description":"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","status":"published","published":"2026-09-07T12:30:29Z","modified":"2026-09-09T15:35:48Z","cvss":[{"version":"4.0","score":5.1,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"},{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T15:11:39.437162Z"}],"nvd":[{"id":"CVE-2026-86351","description":"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","status":"published","published":"2026-09-07T11:17:40.09Z","modified":"2026-09-09T15:26:26.73Z","cvss":[{"version":"4.0","score":5.1,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"},{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-20","CWE-601"],"updated_at":"2026-11-02T14:12:44.082631Z"}],"osv":[{"id":"CVE-2026-86351","title":"MISP User Homepage Validation Allows Authenticated Open Redirect via Protocol-Relative URL","description":"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","status":"published","published":"2026-09-07T09:59:34.85Z","modified":"2026-10-28T02:30:30.437795934Z","cvss":[{"version":"4.0","score":5.1,"vector":"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","level":"medium"}],"cwes":["CWE-20","CWE-601"],"updated_at":"2026-11-02T15:45:18.825071Z"}]}}