# CVE-2026-15305: TYPO3 CMS unrestricted file upload in Form Framework

Source: https://junglewise.ai/threats/cve-2026-15305-typo3-cms-unrestricted-file-upload-in-form-framework  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-14. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-15305 · Severity: medium · CVSS 4 · Published 2026-07-14

TYPO3's Form Framework is used to create and manage web forms on websites. This vulnerability allows attackers to upload files with arbitrary MIME types to forms that have file upload fields, bypassing the intended file type restrictions. While PHP files cannot be uploaded, an attacker could upload other dangerous file types (such as SVG with embedded scripts or other executable formats) to compromise website integrity or inject malicious content.

Technologies: [typo3/cms-form (Packagist)](https://junglewise.ai/threats/technologies/typo3-cms-form). Vendors: [Packagist](https://junglewise.ai/threats/vendors/packagist), [Typo3](https://junglewise.ai/threats/vendors/typo3).

## Quick answers

**Is CVE-2026-15305 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-15305 being exploited in the wild.

**How severe is CVE-2026-15305?** Medium severity, with a CVSS score of 4, published 14 July 2026.

**Which products and versions are affected?** typo3/cms-form (Packagist) >= 14.2.0, <= 14.3.4, ECOSYSTEM:introduced=14.2.0,fixed=14.3.5; TYPO3 CMS Form Framework 14.2.0 to 14.3.4.

**Is there a fix for CVE-2026-15305?** Yes. typo3/cms-form (Packagist): upgrade to 14.3.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-15305 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-15305?** Check whether you run typo3/cms-form (Packagist) or TYPO3 CMS Form Framework at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- typo3/cms-form (Packagist): upgrade to 14.3.5 or later

  ```sh
  composer require typo3/cms-form:^14.3.5
  ```


## Technical details

The vulnerability is a server-side validation bypass in TYPO3's Form Framework (CWE-351: Insufficient Type Distinction). The MimeTypeValidator is instantiated during form construction before concrete form definition properties (such as allowedMimeTypes restrictions) are applied to the form instance. As a result, the validator never participates in the form processing pipeline, allowing FileUpload and ImageUpload elements to accept files of any MIME type regardless of configured restrictions. The attack requires network access to a TYPO3 instance with affected form components but no authentication or user interaction beyond form submission. Although PHP execution is prevented by other mechanisms, attackers can still upload malicious file types to alter website content or deliver payloads. The fix is available in TYPO3 version 14.3.5 LTS and later.

## Affected products

- TYPO3 CMS Form Framework 14.2.0 to 14.3.4

## Identifiers

- CVE-2026-15305
- GHSA-mfqj-cqv3-h7xw

## Timeline

- 2026-08-17: disclosed: Advisory published to GitHub
- 2026-08-31: patched: Fix released in TYPO3 14.3.5 LTS

## References

- [https://api.github.com/users/brosua](https://api.github.com/users/brosua)
- [https://github.com/brosua](https://github.com/brosua)
- [https://api.github.com/users/brosua/gists%7B/gist_id%7D](https://api.github.com/users/brosua/gists%7B/gist_id%7D)
- [https://api.github.com/users/brosua/repos](https://api.github.com/users/brosua/repos)
- [https://avatars.githubusercontent.com/u/34569593?v=4](https://avatars.githubusercontent.com/u/34569593?v=4)
- [https://api.github.com/users/brosua/events%7B/privacy%7D](https://api.github.com/users/brosua/events%7B/privacy%7D)

## Related threats

- [TYPO3 CMS Form Framework unrestricted file upload](https://junglewise.ai/threats/typo3-cms-form-framework-unrestricted-file-upload-4ceedc0d)
- [TYPO3 CMS broken access control in Form Framework form_definition table](https://junglewise.ai/threats/cve-2026-49741-typo3-cms-broken-access-control-in-form-framework-form-definition)
- [TYPO3 CMS privilege escalation in Form Framework via mixed-case extensions](https://junglewise.ai/threats/cve-2026-47346-typo3-cms-privilege-escalation-in-form-framework-via-mixed-case)
- [TYPO3 CMS privilege escalation in Form Framework](https://junglewise.ai/threats/cve-2026-11607-typo3-cms-privilege-escalation-in-form-framework)
- [TYPO3 Form Framework Module vulnerable to Cross-Site Request Forgery](https://junglewise.ai/threats/cve-2024-55922-typo3-form-framework-module-vulnerable-to-cross-site-request)