{"id":"CVE-2026-45118","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-45118","summary":"MyBB is free and open source forum software. Prior to 1.8.40, the Contact module does not validate a redirect URL or protocol correctly, resulting in an open redirect and reflected…","details":"MyBB is free and open source forum software. Prior to 1.8.40, the Contact module does not validate a redirect URL or protocol correctly, resulting in an open redirect and reflected JavaScript code injection. contact.php accepts the redirect target from the from HTTP parameter in $mybb->input['from'] or the Referer HTTP header in $_SERVER['HTTP_REFERER'] and passes it to redirect() without sufficient verification. A javascript: URI becomes the target of the `Click here if you don't want to wait any longer` link because $force_redirect is true, allowing script execution when a victim selects the link. This issue is fixed in version 1.8.40.","published":"2026-08-18T16:17:06.633","modified":"2026-08-18T16:17:06.633","cvss":{"score":9.3,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":null,"references":[{"type":"WEB","url":"https://github.com/mybb/mybb/releases/tag/mybb_1840"},{"type":"WEB","url":"https://github.com/mybb/mybb/security/advisories/GHSA-wf92-5q5h-qr53"},{"type":"WEB","url":"https://mybb.com/versions/1.8.40"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-08-18T16:17:06.633"}}