CVE-2026-58054

HIGH8.6

MyBB - Privilege Escalation from Limited ACP User Management to Administrator

Published Jun 28, 2026

Modified 1 weeks ago

Details

MyBB 1.8.40 does not restrict which usergroup a limited Admin Control Panel user may assign when creating or editing users; the user module offers the Administrators group (gid 4) and its datahandler's verify_usergroup() unconditionally returns true. An admin holding only the delegated user-management permission can assign the Administrators group to an account and escalate to the full Administrator permission set.

References

DETECTION

https://github.com/bikini/exploitarium/tree/main/mybb-limited-acp-to-admin

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-58054

ADVISORY

https://www.vulncheck.com/advisories/mybb-privilege-escalation-from-limited-acp-user-management-to-administrator

CVSS Analysis

CVSS v4.0

8.6

Exploitability

Attack Vector