VulnerabilityDeferred

CVE-2026-47245

MyBB is free and open source forum software.

MEDIUM 4.3EPSS 0.27%

Does this matter?

Lower severity and a low EPSS score (0.27%). Track it; it rarely justifies an emergency change on its own.

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 3.1: 4.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
EPSS: 0.27% probability · 19th percentile
CISA KEV: Not listed
Weakness: CWE-252
Source: security-advisories@github.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.