GHSA-985r-q3qp-299h: Thorsten/phpmyfaq PhpMyFAQ Has An Incomplete Fix Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-985r-q3qp-299h",
  "modified" : "2026-06-26T21:23:37Z",
  "published" : "2026-06-26T21:23:37Z",
  "aliases" : [ ],
  "summary" : "phpMyFAQ has an incomplete fix for GHSA-xvp4-phqj-cjr3 — editUser() and updateUserRights() lack authorization guards",
  "details" : "## Advisory / Disclosure\n\n# phpMyFAQ 4.1.3 — incomplete fix for the admin-API IDOR/privilege-escalation class\n\n**Target:** thorsten/phpMyFAQ (composer: `thorsten/phpmyfaq`, `phpmyfaq/phpmyfaq`)\n**Affected:** <= 4.1.3 (the 4.1.3 security fix is incomplete; siblings remain)\n**Class:** CWE-862 Missing Authorization / CWE-269 Improper Privilege Management / CWE-639 Authorization Bypass Through User-Controlled Key\n**Methodology:** M1 incomplete-fix audit (sibling-walk of the 4.1.3 fix for GHSA-xvp4-phqj-cjr3)\n**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)\n\n## Summary\n\nphpMyFAQ 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:\n\n> \"Only SuperAdmins may change other users' [attributes]. Self-service is\n> always allowed.\" and \"a non-SuperAdmin must never be able to alter a\n> SuperAdmin or protected account.\"\n\nThat 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:\n\n| Endpoint | Route | Sink | Guard in 4.1.3 |\n|----------|-------|------|----------------|\n| `overwritePassword()` | `admin/api/user/overwrite-password` | `changePassword()` | **isSelf + isSuperAdmin + target-protection** (patched) |\n| `editUser()` | `admin/api/user/edit` | `setSuperAdmin((bool)$req.is_superadmin)` | **none** (only `userHasPermission(USER_EDIT)`) |\n| `updateUserRights()` | `admin/api/user/update-rights` | `grantUserRight($req.userId, …)` | **none** (only `userHasPermission(USER_EDIT)`) |\n\nA logged-in administrator holding the delegable `edit_user` right — but  **not** SuperAdmin — can therefore:\n\n1. Set their own (or anyone's) `is_superadmin` flag to `true` via `admin/api/user/edit` → **full privilege escalation to SuperAdmin**.\n2. Grant arbitrary rights to any account via `admin/api/user/update-rights`.\n\nThis is exactly the threat model the parent advisory (GHSA-xvp4) calls out: \"organizations with multiple admin users where not all should have SuperAdmin access.\"\n\n## Anchors (upstream tag 4.1.3)\n\n- `phpmyfaq/src/phpMyFAQ/Controller/Administration/Api/UserController.php`\n  - `editUser()` lines 419-476; user-controlled `userId` at :433, user-controlled `is_superadmin` at :443, sink \n`$user >setSuperAdmin((bool)$isSuperAdmin)` at **:463**. Only gate: `userHasPermission(PermissionType::USER_EDIT)` at :422.\n  - `updateUserRights()` lines 482-520; `userId` at :496, sink `grantUserRight($userId, …)` at **:511**. Only gate at :485.\n  - `overwritePassword()` lines 419… → 228-288; the **patched** guards at: 254-260 and: 269-273.\n- `phpmyfaq/src/phpMyFAQ/Controller/AbstractController.php` —`userHasPermission()` :221-227 (checks one right only; non SuperAdmins can hold it).\n- `phpmyfaq/src/phpMyFAQ/User.php` — `setSuperAdmin()` :950-962 (`UPDATE faquser SET is_superadmin=… WHERE user_id=…`, no guard); `isSuperAdmin()` :942-945.\n- `phpmyfaq/src/phpMyFAQ/Permission/BasicPermission.php` — `hasPermission()` :95-112 (SuperAdmin short-circuits true, else  `checkUserRight`).\n\nEvidence snapshots in this folder:\n`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`.\n\n## Proof of Concept\n\n`poc/poc.php` (run log: `poc/run-log.txt`). Dependency-free: it builds phpMyFAQ's **real schema** (copied verbatim from\n`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:\n\n- Seeds a SuperAdmin (`admin`, id=1) and a non-SuperAdmin admin (`editor`, id=2) granted only `add_user`/`edit_user`/`delete_user`.\n- **Control:** the patched `overwritePassword` guard blocks `editor` changing the SuperAdmin (id=1) — confirms the fix works *there*.\n- **Exploit 1:** `editor` (non-SuperAdmin, passes `userHasPermission(edit_user)`) flips their own `is_superadmin` 0→1 → SuperAdmin. `VULNERABLE`.\n- **Exploit 2:** `editor` grants the `editconfig` right via `updateUserRights`. `VULNERABLE`.\n\nRun:\n```sh\nphp poc/poc.php   # -> RESULT: VULNERABLE ... EXIT 0\n```\n\n### PoC scope (honest)\n\nThe 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.\n\n## Recommended fix\n\nApply the `overwritePassword` invariant to the siblings:\n- `editUser()`: reject `is_superadmin`/status/2FA changes unless `$this->currentUser->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).\n- `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.\n- `activate()` (`admin/api/user/activate`, :194-221) is a lower-impact sibling with the same shape — apply the same guard.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "thorsten/phpmyfaq"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.3"
    }
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "phpmyfaq/phpmyfaq"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.3"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/thorsten/phpMyFAQ/security/advisories/GHSA-985r-q3qp-299h"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/thorsten/phpMyFAQ"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-832" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-26T21:23:37Z",
    "nvd_published_at" : null
  }
}