CVE-2026-58054
MyBB - Privilege Escalation from Limited ACP User Management to Administrator
CVSS Score
7.2
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-269 |
| Vendor | mybb |
| Product | mybb |
| Published | Jun 28, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
MyBB / MyBB
0 ≤ 1.8.40
References
Credits
ashdfrkl