CVE-2026-58054 HIGH

CVE-2026-58054: MyBB - Privilege Escalation from Limited ACP User Management to Administrator

Vendor Mybb
Product MyBB
Weakness CWE-269
Published June 28, 2026
Last update June 29, 2026
View on NVD All CVEs

CVSS base score

7.2/10
Attack vector Network
Attack complexity Low
Privileges required High
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

June 28, 2026 CVE published
June 29, 2026 Record updated