CVE-2026-56396

phpMyFAQ before 4.1.4 contains missing authorization vulnerabilities in editUser() and updateUserRights() endpoints that allow authenticated administrators to escalate privileges. Non-SuperAdmin users with edit_user permission can set is_superadmin flag or grant arbitrary rights to escalate to SuperAdmin access.

phpMyFAQ before 4.1.4 contains missing authorization vulnerabilities in editUser() and updateUserRights() endpoints that allow authenticated administrators to escalate privileges. Non-SuperAdmin users with edit_user permission can set is_superadmin flag or grant arbitrary rights to escalate to SuperAdmin access.

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 $user >setSuperAdmin((bool)$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),…

phpMyFAQ before 4.1.4 contains missing authorization vulnerabilities in editUser() and updateUserRights() endpoints that allow authenticated administrators to escalate privileges. Non-SuperAdmin users with edit_user permission can set is_superadmin flag or grant arbitrary rights to escalate to SuperAdmin access.

phpMyFAQ before 4.1.4 contains missing authorization vulnerabilities in editUser() and updateUserRights() endpoints that allow authenticated administrators to escalate privileges. Non-SuperAdmin users with edit_user permission can set is_superadmin flag or grant arbitrary rights to escalate to SuperAdmin access.

phpMyFAQ before 4.1.4 contains missing authorization vulnerabilities in editUser() and updateUserRights() endpoints that allow authenticated administrators to escalate privileges. Non-SuperAdmin users with edit_user permission can set is_superadmin flag or grant arbitrary rights to escalate to SuperAdmin access.

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 $user >setSuperAdmin((bool)$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),…