CVE-2026-15305: TYPO3 CMS

Medium severity, CVSS 6.3. EPSS: 0.3% chance of exploitation in the next 30 days.

Users were able to upload files with arbitrary MIME types to forms using FileUpload or ImageUpload elements with allowedMimeTypes configured. The restriction was not enforced server-side because the MimeTypeValidator was registered during form building before concrete form definition properties were applied, resulting in the validator never being added to the processing pipeline. This issue affects TYPO3 CMS versions 14.2.0-14.3.4.

Affected products

• TYPO3 TYPO3 CMS: from 14.2.0, before 14.3.5 (fixed in 14.3.5)

Published 2026-07-14. Last modified 2026-09-03.