{"id":"CVE-2026-45127","title":"MyBB is free and open source forum software","summary":"MyBB is free and open source forum software. Prior to 1.8.40, the ACP Mass Mail module does not validate certain requests correctly, allowing same-site attackers to create draft entries from archived entries by embedding a specially craf…","severity":"low","cvss":3.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N","cwe":["CWE-352"],"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-2026-45127","references":[{"url":"https://github.com/mybb/mybb/commit/a95c5d6730b943adab7e54bc209c051f98843a3b","label":"security-advisories@github.com"},{"url":"https://github.com/mybb/mybb/releases/tag/mybb_1840","label":"security-advisories@github.com"},{"url":"https://github.com/mybb/mybb/security/advisories/GHSA-xx78-g79m-qvgq","label":"security-advisories@github.com"},{"url":"https://mybb.com/versions/1.8.40","label":"security-advisories@github.com"}],"tags":["nvd"],"epss":0.00132,"epssPercentile":0.03149,"ingestedAt":"2026-09-08T21:11:12.280Z","slug":"CVE-2026-45127","body":"## Overview\n\nMyBB is free and open source forum software. Prior to 1.8.40, the ACP Mass Mail module does not validate certain requests correctly, allowing same-site attackers to create draft entries from archived entries by embedding a specially crafted URL. The Resend route in Admin CP, Users & Groups, Mass Mail, Mass Mailing Archive duplicates archived mailing entries into new drafts with mybb_massemails.status set to 0 on GET requests without request forgery protection. The uniquely identifying implementation details include Users & Groups → Mass Mail → Mass Mailing Archive, mybb_massemails.status = 0, and admin/modules/user/mass_mail.php. 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":"sunlit","depthScore":19,"depthScoreParts":{"impact":19.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}