CVE-2026-45008: phpMyFAQ Path Traversal Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gh9p-q46p-57g2",
  "modified" : "2026-06-09T00:00:57Z",
  "published" : "2026-05-06T20:47:54Z",
  "aliases" : [ "CVE-2026-45008" ],
  "summary" : "phpMyFAQ: Path Traversal in Client::deleteClientFolder enables arbitrary directory deletion by non-super-admin admins",
  "details" : "## Summary\n\n`Client::deleteClientFolder()` in `phpmyfaq/src/phpMyFAQ/Instance/Client.php:583` takes a URL from the caller, strips the `https://` prefix, and passes the remainder to `Filesystem::deleteDirectory()` relative to the multisite `clientFolder`. No path-traversal validation runs. An admin with the `INSTANCE_DELETE` permission (a role short of SUPER_ADMIN) submits `https://../../../<path>` as the client URL and the server recursively deletes arbitrary directories under the web user's rights. Same pattern and reachability as GHSA-38m8-xrfj-v38x, which the project accepted at High severity three weeks earlier.\n\n## Details\n\n`phpmyfaq/src/phpMyFAQ/Instance/Client.php:583-591`:\n\n```php\npublic function deleteClientFolder(string $sourceUrl): bool\n{\n    if (!$this->isMultiSiteWriteable()) {\n        return false;\n    }\n\n    $sourcePath = str_replace(search: 'https://', replace: '', subject: $sourceUrl);\n    return $this->filesystem->deleteDirectory($this->clientFolder . $sourcePath);\n}\n```\n\n`str_replace` strips the scheme but does nothing about `../` segments. The concatenation `$this->clientFolder . $sourcePath` directly feeds the filesystem call, which traverses above `clientFolder` without complaint.\n\nCallers feed the URL from the HTTP request body:\n\n`phpmyfaq/src/phpMyFAQ/Controller/Administration/Api/InstanceController.php:184`:\n\n```php\nif (1 !== $instanceId && $client->deleteClientFolder($clientData->url) && $client->delete($instanceId)) {\n```\n\n`$clientData->url` comes from `json_decode($request->getContent())`. The route is `admin.api.instance.delete`, gated by `INSTANCE_DELETE`. The controller does not validate the URL against a scheme list or canonicalize the path before handing it to `deleteClientFolder()`.\n\n`InstanceController.php:144` (edit path) and `Controller/Administration/InstanceController.php:151` (form path) both reach the same sink through different entry points.\n\n### Precedent\n\nGHSA-38m8-xrfj-v38x (2026-03-31) disclosed the identical bug class in `MediaBrowserController::index()`: an admin-gated API endpoint concatenates a user-supplied filename to a base directory without traversal validation. phpMyFAQ accepted that report at High severity. The present finding is the same root cause in a different controller; the project's INSTANCE_ADD / INSTANCE_DELETE permission is a granular admin right, not SUPER_ADMIN, so a lower-tier admin can reach the sink.\n\n## Proof of Concept\n\nPrerequisites: a phpMyFAQ 4.2.x instance with the multisite subsystem bootstrapped (there must be a non-primary instance present for the delete controller branch to fire). Alice is an admin with `INSTANCE_ADD` and `INSTANCE_DELETE` rights, no `SUPER_ADMIN` flag.\n\nStep 1: Alice authenticates and retrieves the CSRF token for the instance admin page.\n\nStep 2: Alice creates an instance whose `url` encodes a traversal payload. The create path at `InstanceController.php:144` already concatenates to the clientFolder through the same `deleteClientFolder(`'https://' . $hostname`)` call:\n\n```bash\ncurl -sS -b \"$ALICE_COOKIE\" -X POST \"$BASE/admin/api/instance\" \\\n  -H \"Content-Type: application/json\" -H \"x-csrf-token: $CSRF\" \\\n  -d '{\"url\":\"https://../../../tmp/pmf-poc/\",\"instance\":\"poc\",\"comment\":\"poc\",\"email\":\"a@b\",\"admin\":\"alice\",\"password\":\"poc1234!\"}'\n```\n\nStep 3: Alice deletes the instance. The request body names the instance id to delete; the controller hands `clientData->url` directly to `deleteClientFolder`:\n\n```bash\ncurl -sS -b \"$ALICE_COOKIE\" -X POST \"$BASE/admin/api/instance/2\" \\\n  -H \"Content-Type: application/json\" -H \"x-csrf-token: $CSRF\" \\\n  -d '{\"url\":\"https://../../../tmp/pmf-poc/\"}'\n```\n\nThe server computes `$sourcePath = '../../../tmp/pmf-poc/'`, concatenates to `<clientFolder>/`, and recursively deletes the resulting path.\n\nLive verification was not attempted against the test instance because the INSTANCE_DELETE path requires the multisite/ subsystem to be bootstrapped with at least one non-primary instance; see `InstanceController.php:184`. The code path is unambiguous and the precedent GHSA confirmed the same admin gating was considered in-scope.\n\n## Impact\n\nAny phpMyFAQ admin holding `INSTANCE_ADD` + `INSTANCE_DELETE` but not SUPER_ADMIN can delete arbitrary directories writable by the PHP process. Outcomes:\n\n- Destroy other tenants' data on a shared multisite deployment by traversing above the `clientFolder` into peer directories.\n- Delete phpMyFAQ's own `content/`, `config/`, or cache directories and lock the install out.\n- On a hosted deployment, overwrite or delete files anywhere under the web user's reach, including customer uploads outside phpMyFAQ.\n\nphpMyFAQ's permission model gives `INSTANCE_ADD` / `INSTANCE_DELETE` as a role that a hosting operator may delegate to a subordinate admin without granting SUPER_ADMIN. That delegation is now a direct path-traversal-delete primitive.\n\n## Recommended Fix\n\nCanonicalize and validate the URL before forming the filesystem path.\n\n`phpmyfaq/src/phpMyFAQ/Instance/Client.php:583`:\n\n```php\npublic function deleteClientFolder(string $sourceUrl): bool\n{\n    if (!$this->isMultiSiteWriteable()) {\n        return false;\n    }\n\n    $parsed = parse_url($sourceUrl);\n    if (!is_array($parsed) || !isset($parsed['host']) || ($parsed['scheme'] ?? '') !== 'https') {\n        return false;\n    }\n\n    $host = $parsed['host'];\n    if (!preg_match('/^[a-z0-9][a-z0-9.-]*$/i', $host)) {\n        return false;\n    }\n\n    $target = realpath($this->clientFolder . $host);\n    $root = realpath($this->clientFolder);\n    if ($target === false || $root === false || !str_starts_with($target, $root . DIRECTORY_SEPARATOR)) {\n        return false;\n    }\n\n    return $this->filesystem->deleteDirectory($target);\n}\n```\n\n`parse_url` rejects malformed inputs, the regex pins the host to valid DNS characters (no `/`, no `..`), and the `realpath` check ensures the resolved target lives under `clientFolder`. Apply the same canonicalization at the controller layer (`InstanceController::add`, `::update`, `::delete`) so the URL is validated before every call that touches the filesystem.\n\n---\n*Found by [aisafe.io](https://aisafe.io)*",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "thorsten/phpmyfaq"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.1"
    }
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "phpmyfaq/phpmyfaq"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/thorsten/phpMyFAQ/security/advisories/GHSA-gh9p-q46p-57g2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-45008"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/thorsten/phpMyFAQ"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/phpmyfaq-path-traversal-in-client-deleteclientfolder-via-url-parameter"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-06T20:47:54Z",
    "nvd_published_at" : null
  }
}