CVE-2026-47245 PUBLISHED

MyBB: Buddy list corruption

Assigner: GitHub_M
Reserved: 18.05.2026 Published: 18.08.2026 Updated: 18.08.2026

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.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CVSS Score: 4.3

Product Status

Vendor mybb
Product mybb
Versions
  • Version < 1.8.40 is affected

References

Problem Types

  • CWE-252: Unchecked Return Value CWE