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GHSA-mfqj-cqv3-h7xw

Fix: TYPO3/typo3@817ad41

GHSA-mfqj-cqv3-h7xw is a CWE-351 vulnerability in typo3/cms-form. O3 Security confirms whether GHSA-mfqj-cqv3-h7xw is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

TYPO3 CMS - Unrestricted File Upload in Form Framework

Also known asCVE-2026-15305
Published
Aug 31, 2026
Updated
Aug 31, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Aug 31, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
🐘typo3/cms-form

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Problem

Users were able to upload files with arbitrary MIME types to forms using FileUpload or ImageUpload elements with allowedMimeTypes configured - uploading PHP files was not possible. 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.

Solution

Update to TYPO3 version 14.3.5 LTS that fixes the problem described.

Credits

Thanks to Sébastien Convers for reporting this issue, and to Josua Vogel and Oliver Hader for fixing it.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagisttypo3/cms-form≥ 14.2.0&&< 14.3.514.3.5

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for typo3/cms-form. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update typo3/cms-form to 14.3.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mfqj-cqv3-h7xw is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-mfqj-cqv3-h7xw is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-mfqj-cqv3-h7xw. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Problem Users were able to upload files with arbitrary MIME types to forms using _FileUpload_ or _ImageUpload_ elements with _allowedMimeTypes_ configured - uploading PHP files was **not** possible. 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. ### Solution Update to TYPO3 version 14.3.5 LTS that fixes the problem described. ### Credits Thanks to Sébastien Convers for reporting this issue, and
O3 Security · Impact-Aware SCA

Is GHSA-mfqj-cqv3-h7xw in your dependencies?

O3 detects GHSA-mfqj-cqv3-h7xw across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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GHSA-mfqj-cqv3-h7xw: typo3/cms-form | O3 Security