{"id":"CVE-2026-45118","title":"MyBB is free and open source forum software","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 JavaScript code injection. contact.php accepts the redir…","severity":"critical","cvss":9.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","cwe":["CWE-83"],"published":"2026-08-18","updated":"2026-09-08","sourceUpdated":"2026-09-08T21:02:26.047","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-45118","references":[{"url":"https://github.com/mybb/mybb/releases/tag/mybb_1840","label":"security-advisories@github.com"},{"url":"https://github.com/mybb/mybb/security/advisories/GHSA-wf92-5q5h-qr53","label":"security-advisories@github.com"},{"url":"https://mybb.com/versions/1.8.40","label":"security-advisories@github.com"}],"tags":["nvd"],"epss":0.00384,"epssPercentile":0.32311,"ingestedAt":"2026-09-08T21:11:12.280Z","slug":"CVE-2026-45118","body":"## Overview\n\nMyBB 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":51,"depthScoreParts":{"impact":51.2,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}