CVE-2025-47939

Problem

By design, the file management module in TYPO3’s backend user interface has historically allowed the upload of any file type, with the exception of those that are directly executable in a web server context. This lack of restriction means it is possible to upload files that may be considered potentially harmful, such as executable binaries (e.g., .exe files), or files with inconsistent file extensions and MIME types (for example, a file incorrectly named with a .png extension but actually carrying the MIME type application/zip).

Although such files are not directly executable through the web server, their presence can introduce indirect risks. For example, third-party services such as antivirus scanners or malware detection systems might flag or block access to the website for end users if suspicious files are found. This could negatively affect the availability or reputation of the site.

Credits

Thanks to Hamed Kohi for reporting this issue, and to TYPO3 core & security team member Oliver Hader for fixing it.

The application accepts file uploads without adequately restricting the file type or content. Typical impact: remote code execution if the uploaded file can be served and executed on the server.

CVE-2025-47939 has a CVSS score of 5.4 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (9.5.51, 10.4.50, 11.5.44, 12.4.31, 13.4.12); upgrading removes the vulnerable code path.

Kodem intelligence

Update to TYPO3 versions 9.5.51 ELTS, 10.4.50 ELTS, 11.5.44 ELTS, 12.4.31 LTS, 13.4.12 LTS that fix the problem described.

[!NOTE]
The mitigation strategies outlined below apply broadly to all file uploads handled through TYPO3's File Abstraction Layer (FAL), not just those performed via the backend interface. This means that any extension or custom integration leveraging FAL will also be subject to the new validation rules and configuration options. Developers are advised to review the implications for their code and refer to the documentation of that change for guidance.

[!IMPORTANT]

Strong security defaults - Manual actions required

These versions introduce new configuration options to better control which files are permitted for upload and to improve consistency checks.

A new configuration option, $GLOBALS['TYPO3_CONF_VARS']['SYS']['miscfile_ext'], has been added. This option allows administrators to explicitly define which file extensions should be permitted that are not already part of the built-in text or media file groups - examples include archive formats such as zip or xz.

In addition, two new feature flags have been introduced to enhance security:

• security.system.enforceAllowedFileExtensions, enforces the defined list of allowed file extensions. This flag is enabled by default in new TYPO3 installations, but remains disabled in existing installations to prevent breaking changes.
• security.system.enforceFileExtensionMimeTypeConsistency, ensures that the uploaded file’s extension matches its actual MIME type, providing further validation of file integrity. This flag is active by default.

It is recommended to configure the allowed file extensions via $GLOBALS['TYPO3_CONF_VARS']['SYS']['miscfile_ext'] and to enable the feature flag security.system.enforceAllowedFileExtensions to enforce the restriction.

1. What is CVE-2025-47939? CVE-2025-47939 is a medium-severity unrestricted upload of dangerous file types vulnerability in typo3/cms-core (composer), affecting versions >= 9.0.0, <= 9.5.50. It is fixed in 9.5.51, 10.4.50, 11.5.44, 12.4.31, 13.4.12. The application accepts file uploads without adequately restricting the file type or content.
2. How severe is CVE-2025-47939? CVE-2025-47939 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of typo3/cms-core are affected by CVE-2025-47939? typo3/cms-core (composer) versions >= 9.0.0, <= 9.5.50 is affected.
4. Is there a fix for CVE-2025-47939? Yes. CVE-2025-47939 is fixed in 9.5.51, 10.4.50, 11.5.44, 12.4.31, 13.4.12. Upgrade to this version or later.
5. Is CVE-2025-47939 exploitable, and should I be worried? Whether CVE-2025-47939 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-47939 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-47939?
   • Upgrade typo3/cms-core to 9.5.51 or later
   • Upgrade typo3/cms-core to 10.4.50 or later
   • Upgrade typo3/cms-core to 11.5.44 or later
   • Upgrade typo3/cms-core to 12.4.31 or later
   • Upgrade typo3/cms-core to 13.4.12 or later