Vulnerability Description
MyBB is free and open source forum software. Prior to 1.8.40, the User CP Buddy/Ignore List component does not validate reciprocal buddy-list updates correctly. The usercp.php?action=do_editlists delete handler removes the selected entry from the acting user's list and then updates mybb_users.buddylist for the target account. The reciprocal update searches for the deleted target UID instead of the acting user's UID and uses the unchecked array_search() return value as an array key. A false result can be converted to index 0, removing the target account's first stored buddy while leaving the actual reciprocal entry unchanged. The uniquely identifying implementation details include false converted to index 0. This issue is fixed in version 1.8.40.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/mybb/mybb/commit/0557718f27503034fb1c2768729a2fb8239bba65
- https://github.com/mybb/mybb/releases/tag/mybb_1840
- https://github.com/mybb/mybb/security/advisories/GHSA-w8gm-j57p-jqpc
- https://mybb.com/versions/1.8.40
FAQ
What is CVE-2026-47245?
CVE-2026-47245 is a vulnerability with a CVSS score of 4.3 (MEDIUM). MyBB is free and open source forum software. Prior to 1.8.40, the User CP Buddy/Ignore List component does not validate reciprocal buddy-list updates correctly. The usercp.php?action=do_editlists dele...
How severe is CVE-2026-47245?
CVE-2026-47245 has been rated MEDIUM with a CVSS base score of 4.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-47245?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.