CVE-2026-58054
HIGHMyBB - Privilege Escalation from Limited ACP User Management to Administrator
Title source: cnaDescription
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 (2)
Core 2
Core References
Exploit exploit
third-party-advisory
Proof of Concept
https://github.com/bikini/exploitarium/tree/main/mybb-limited-acp-to-admin
Third Party Advisory third-party-advisory
VulnCheck Advisory: MyBB - Privilege Escalation from Limited ACP User Management to Administrator
https://www.vulncheck.com/advisories/mybb-privilege-escalation-from-limited-acp-user-management-to-administrator
Scores
CVSS v3
7.2
EPSS
0.0027
EPSS Percentile
19.0%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
total
Details
CWE
CWE-269
Status
published
Products (1)
MyBB/MyBB
< 1.8.40
Published
Jun 28, 2026
Tracked Since
Jun 28, 2026