CVE-2026-58054

high

Description

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

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

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

Details

Source: Mitre, NVD

Published: 2026-06-28

Updated: 2026-06-28

Risk Information

CVSS v2

Base Score: 8.3

Vector: CVSS2#AV:N/AC:L/Au:M/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 7.2

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

Severity: High

CVSS v4

Base Score: 8.6

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Severity: High