Vulnerability Database

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phpMyFAQ has an incomplete fix for GHSA-xvp4-phqj-cjr3 — editUser() and updateUserRights() lack authorization guards — thorsten / phpmyfaq

Unlock of a Resource that is not Locked

Advisory / Disclosure

phpMyFAQ 4.1.3 — incomplete fix for the admin-API IDOR/privilege-escalation class

Target: thorsten/phpMyFAQ (composer: thorsten/phpmyfaq, phpmyfaq/phpmyfaq) Affected: <= 4.1.3 (the 4.1.3 security fix is incomplete; siblings remain) Class: CWE-862 Missing Authorization / CWE-269 Improper Privilege Management / CWE-639 Authorization Bypass Through User-Controlled Key Methodology: M1 incomplete-fix audit (sibling-walk of the 4.1.3 fix for GHSA-xvp4-phqj-cjr3) Severity: High — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H = 8.8 (same class as the parent CVE)

Summary

phpMyFAQ 4.1.3 fixed GHSA-xvp4-phqj-cjr3 ("IDOR Account Takeover") by adding actor-authorization guards to UserController::overwritePassword(). The patch establishes a new invariant, stated in its own code comments:

> "Only SuperAdmins may change other users' [attributes]. Self-service is > always allowed." and "a non-SuperAdmin must never be able to alter a > SuperAdmin or protected account."

That invariant is not enforced on two sibling endpoints in the same file, which the 4.1.3 fix left unchanged, and which carry the identical "user-controlled userId → getUserById() → privileged mutation" primitive — but with a strictly more dangerous sink:

| Endpoint | Route | Sink | Guard in 4.1.3 | |----------|-------|------|----------------| | overwritePassword() | admin/api/user/overwrite-password | changePassword() | isSelf + isSuperAdmin + target-protection (patched) | | editUser() | admin/api/user/edit | setSuperAdmin((bool)$req.is_superadmin) | none (only userHasPermission(USER_EDIT)) | | updateUserRights() | admin/api/user/update-rights | grantUserRight($req.userId, …) | none (only userHasPermission(USER_EDIT)) |

A logged-in administrator holding the delegable edit_user right — but not SuperAdmin — can therefore:

  1. Set their own (or anyone's) is_superadmin flag to true via admin/api/user/edit → full privilege escalation to SuperAdmin.
  2. Grant arbitrary rights to any account via admin/api/user/update-rights.

This is exactly the threat model the parent advisory (GHSA-xvp4) calls out: "organizations with multiple admin users where not all should have SuperAdmin access."

Anchors (upstream tag 4.1.3)

  • phpmyfaq/src/phpMyFAQ/Controller/Administration/Api/UserController.php
    • editUser() lines 419-476; user-controlled userId at :433, user-controlled is_superadmin at :443, sink $user &gt;setSuperAdmin((bool)$isSuperAdmin) at :463. Only gate: userHasPermission(PermissionType::USER_EDIT) at :422.
    • updateUserRights() lines 482-520; userId at :496, sink grantUserRight($userId, …) at :511. Only gate at :485.
    • overwritePassword() lines 419… → 228-288; the patched guards at: 254-260 and: 269-273.
  • phpmyfaq/src/phpMyFAQ/Controller/AbstractController.php —userHasPermission() :221-227 (checks one right only; non SuperAdmins can hold it).
  • phpmyfaq/src/phpMyFAQ/User.php — setSuperAdmin() :950-962 (UPDATE faquser SET is_superadmin=… WHERE user_id=…, no guard); isSuperAdmin() :942-945.
  • phpmyfaq/src/phpMyFAQ/Permission/BasicPermission.php — hasPermission() :95-112 (SuperAdmin short-circuits true, else checkUserRight).

Evidence snapshots in this folder: advisory/fix-diff-4.1.2-to-4.1.3.txt (proves the fix touched only overwritePassword/deleteUser) and advisory/vulnerable-siblings-4.1.3.txt (the two unguarded methods as shipped). git diff 4.1.2 4.1.3 shows no change to editUser, updateUserRights, setSuperAdmin, or grantUserRight.

Proof of Concept

poc/poc.php (run log: poc/run-log.txt). Dependency-free: it builds phpMyFAQ's real schema (copied verbatim from src/phpMyFAQ/Instance/Database/Sqlite3.php) and executes the verbatim SQL that the shipped 4.1.3 methods run —setSuperAdmin (UPDATE), grantUserRight (INSERT), and the real hasPermission / checkUserRight / getRightId queries — to prove the primitive:

  • Seeds a SuperAdmin (admin, id=1) and a non-SuperAdmin admin (editor, id=2) granted only add_user/edit_user/delete_user.
  • Control: the patched overwritePassword guard blocks editor changing the SuperAdmin (id=1) — confirms the fix works there.
  • Exploit 1: editor (non-SuperAdmin, passes userHasPermission(edit_user)) flips their own is_superadmin 0→1 → SuperAdmin. VULNERABLE.
  • Exploit 2: editor grants the editconfig right via updateUserRights. VULNERABLE.

Run:

php poc/poc.php # -&gt; RESULT: VULNERABLE ... EXIT 0

PoC scope (honest)

The PoC exercises the privilege-escalation primitive (the unguarded sinks + the real authorization-resolution logic) against the real schema. The full HTTP exploit additionally requires an authenticated admin session and a CSRF token (editUser verifies update-user-data, updateUserRights verifies update-user-rights); both are available to the authenticated admin attacker — the parent advisory's own PoC shows reading the CSRF token from admin pages. The controller-level absence of an authorization guard is established by source citation (the only gate is userHasPermission(USER_EDIT)), corroborated by the fix diff showing these methods were not modified.

Apply the overwritePassword invariant to the siblings:

  • editUser(): reject is_superadmin/status/2FA changes unless $this-&gt;currentUser-&gt;isSuperAdmin(); never allow a non-SuperAdmin to edit a SuperAdmin or protected target. Treat is_superadmin as a SuperAdmin-only field (defeat the mass-assignment at :443/:463).
  • updateUserRights(): require isSuperAdmin() (or a privilege-level comparison) before grantUserRight; forbid granting rights the actor does not itself hold, and forbid targeting SuperAdmin/protected users.
  • activate() (admin/api/user/activate, :194-221) is a lower-impact sibling with the same shape — apply the same guard.
  • Published: Jun 26, 2026
  • Updated: Jun 27, 2026
  • GHSA: GHSA-985r-q3qp-299h
  • Severity: High
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: High
  • Score: 8.1
  • AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

CWEs:

Software Affected versions
Composer icon thorsten / phpmyfaq < 4.1.4
Composer icon phpmyfaq / phpmyfaq < 4.1.4

Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

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Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

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