CodeIgniter4 has a validation bypass when uploading file extensions via `ext_in` rule
Impact
The ext_in upload validation rule checked the MIME-derived guessed extension instead of the client-provided filename extension. As a result, an uploaded file named shell.php containing GIF-like content could pass validation such as:
uploaded[avatar]|is_image[avatar]|mime_in[avatar,image/gif]|ext_in[avatar,gif]because the detected MIME type maps to gif, even though the uploaded filename extension is php.
Applications are impacted if they:
- accept user-controlled uploads,
- rely on
ext_into validate the uploaded filename extension, - save uploaded files using the original client filename:
$file->move($path), - store uploads in a web-accessible directory,
- and allow PHP or other executable files to run from that directory.
In those conditions, this may lead to arbitrary code execution. The default application does not expose such an upload endpoint.
Patches
Upgrade to v4.7.3 or later.
Workarounds
- Save uploads outside the public web root, preferably under
writable/uploads - Use
$file->store()or$file->move($path, $file->getRandomName())instead of preserving the original filename - Disable script execution in any public upload directory
- Manually verify the client filename extension before moving the file
- Reject files when
$file->getClientExtension()is not in the allowed list or does not match$file->guessExtension()
Resources
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Paquete de Composer | codeigniter4/framework | < 4.7.3 | 4.7.3 |
Referencias
- https://github.com/codeigniter4/CodeIgniter4/security/advisories/GHSA-2gr4-ppc7-7mhx
- https://github.com/codeigniter4/CodeIgniter4/commit/29299349e7d232e9532767c7cefaed30957309be
- https://codeigniter.com/user_guide/libraries/uploaded_files.html#moving-files
- https://codeigniter.com/user_guide/libraries/validation.html#rules-for-file-uploads
- https://github.com/codeigniter4/CodeIgniter4
- https://github.com/codeigniter4/CodeIgniter4/blob/develop/CHANGELOG.md
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Debilidad (CWE)
CWE-434- Plataforma
- Composer
- Paquete
codeigniter4/framework- Publicada
- 11.06.2026
- Actualizado
- 11.10.2026 10:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-2gr4-ppc7-7mhx - CC BY 4.0
Historial de vulnerabilidades: codeigniter4/framework
Todas las vulnerabilidades publicadas de este paquete (Paquete de Composer), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 19
- Primera → última
- 01.2022 08.2026
- Sin corrección
- 1
- Explotada en ataques
- 0
Distribución por gravedad
- Crítica 6
- Alta 8
- Media 4
- Baja 1
Divulgaciones por año
- 2022: 9
- 2023: 2
- 2024: 1
- 2025: 2
- 2026: 5
-
CodeIgniter4 has a validation bypass when uploading file extensions via `ext_in` rule esta entrada
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