CVE-2026-111891 in phpMyFAQ
Summary
by MITRE • 10/17/2026
phpMyFAQ from 4.2.0-alpha.2 before 4.2.0-beta contains a privilege escalation vulnerability in the group permission API, whose updatePermissions and updateMembers endpoints check held rights without regard to language or category scope and write unrestricted group grants. Non-superadmin administrators holding GROUP_EDIT can grant a group a right they hold only in a narrow scope and self-join it via updateMembers, gaining unrestricted FAQ create, edit, and publish access across all languages and categories.
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Analysis
by VulDB Data Team • 10/17/2026
The vulnerability identified within phpMyFAQ versions prior to 4.2.0-beta represents a critical privilege escalation flaw rooted in the application's group permission management API. Specifically, the endpoints updatePermissions and updateMembers fail to enforce scope constraints when validating user rights against requested actions. In a properly secured multi-tenant or localized content management system, permissions granted for specific categories or languages should remain isolated within those boundaries. However, this implementation allows an administrator with limited privileges to bypass these logical restrictions by directly manipulating group assignments without verifying that the target permission exists globally rather than just locally.
The technical mechanism of exploitation relies on a logic error where the application checks if the requesting user holds a specific right in any context before allowing them to assign that same right to another entity, regardless of scope. An attacker who is an administrator with GROUP_EDIT privileges can identify rights they possess within a narrow subset of content, such as editing FAQs in a single category or language. By invoking the updatePermissions endpoint, they can grant this narrowly scoped right to a group without restriction. Subsequently, using the updateMembers endpoint, they add their own user account to that same group. This self-join effectively elevates their privileges from local administrators with limited scope to global administrators with unrestricted access across all languages and categories within the phpMyFAQ instance.
The operational impact of this vulnerability is severe, as it allows unauthorized users to gain full control over the content management system. Once escalated, the attacker can create, edit, and publish FAQs without any restrictions based on language or category boundaries. This compromises the integrity of the entire knowledge base, potentially leading to data manipulation, defacement, or the insertion of malicious content that affects all users regardless of their regional or categorical access levels. Furthermore, this escalation undermines the principle of least privilege, which is fundamental to secure system design and compliance with security best practices.
From a classification perspective, this vulnerability aligns with CWE-269 Improper Privilege Management, as it involves an actor obtaining privileges that exceed those intended for their role or scope. It also relates to CWE-862 Missing Authorization, where the application fails to ensure that authorized users only access resources and perform actions commensurate with their authorization level. In terms of offensive security frameworks, this behavior is consistent with ATT&CK technique T1078 Valid Accounts, specifically involving legitimate accounts being used to escalate privileges through misconfigured permissions rather than traditional credential theft or exploitation of software bugs in authentication mechanisms.
Mitigation strategies must focus on enforcing strict scope validation within the permission API logic. Developers should ensure that when checking if a user can grant a right, they verify not only that the user holds the right but also that it is held with global applicability or explicitly scoped to match the target group's permissions. Additionally, implementing role-based access control checks at the controller level for both updatePermissions and updateMembers endpoints will prevent unauthorized privilege assignments. Upgrading to version 4.2.0-beta or later resolves this issue by correcting these logical flaws in the permission handling routines. Until an upgrade is performed, administrators should restrict GROUP_EDIT privileges to only those users who require global administrative capabilities and monitor group membership changes for suspicious self-joins or unexpected scope expansions.