CVE-2026-111890 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 UserController::updateUserRights that drops per-right language restrictions when rights are re-granted. Administrators holding USER_EDIT can submit language-scoped rights to the update-rights API, including for themselves, to gain unrestricted FAQ create, edit, and publish access across all languages.
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Analysis
by VulDB Data Team • 10/18/2026
The vulnerability identified in phpMyFAQ versions prior to 4.2.0-beta represents a critical privilege escalation flaw within the application's user management subsystem, specifically located in the UserController::updateUserRights method. This issue stems from an improper implementation of authorization checks and access control mechanisms when handling updates to user permissions. The core technical failure involves the system’s inability to properly enforce language-scoped restrictions during the re-granting or modification of rights. In a correctly secured multi-lingual content management environment, administrative actions that modify user privileges should be strictly bound by the context in which they are requested, ensuring that an administrator can only manage permissions relevant to their own scope or explicitly authorized broader scopes without bypassing inherent security boundaries.
In this specific instance, administrators possessing the USER_EDIT permission were able to exploit a logic error where language restrictions associated with specific rights were inadvertently dropped during the update process. By submitting requests through the update-rights API endpoint, these users could specify permissions that included capabilities such as FAQ creation, editing, and publishing. Crucially, the application failed to validate whether the newly assigned or modified rights respected the existing multi-language isolation policies. This oversight allowed an attacker with limited administrative privileges to escalate their access level by removing language constraints from their own profile or those of other users they could edit. The result was a state where these users gained unrestricted access to create, modify, and publish content across all supported languages within the system, effectively bypassing the intended granular control mechanisms designed to segment data and operations by locale.
The operational impact of this vulnerability is severe, as it compromises both the confidentiality and integrity of the application's content management workflows. An attacker leveraging this flaw can inject malicious or misleading information into any language section of the FAQ database without detection from standard permission audits that rely on role-based access controls rather than context-aware validation. This undermines the trust model of multi-tenant or multi-language deployments where data isolation is paramount for compliance and operational clarity. Furthermore, because the vulnerability allows self-elevation of privileges, it poses a significant risk to internal security postures, enabling insider threats or compromised accounts with minimal initial access to achieve full administrative control over content operations across all linguistic variants supported by the platform.
From an industry standard perspective, this flaw aligns closely with CWE-269 Improper Privilege Management and CWE-862 Missing Authorization, as the application fails to enforce proper restrictions on privileged actions based on user roles and context. Additionally, it reflects aspects of ATT&CK technique T1078 Valid Accounts, where an attacker uses legitimate credentials but exploits a logic flaw to gain higher-level access than intended by the system's design. The failure to maintain state consistency regarding language scopes during permission updates highlights a gap in input validation and business logic security that is critical for applications handling sensitive or regulated content across multiple regions.
To mitigate this vulnerability, it is essential to apply the official patch provided in phpMyFAQ version 4.2.0-beta or later, which addresses the flawed logic within the UserController::updateUserRights method. Developers must ensure that any API endpoint responsible for modifying user permissions strictly validates and preserves language-scoped restrictions unless explicitly authorized by a higher-level security policy. Implementing rigorous input validation on all permission-related fields is crucial to prevent the stripping of contextual constraints during updates. Furthermore, adopting a principle of least privilege in system design ensures that even if such logic errors occur, their impact remains contained within defined boundaries rather than resulting in unrestricted global access. Regular security audits focusing on authorization checks and multi-tenant isolation patterns can help identify similar weaknesses before they are exploited in production environments.