TYPO3 CMS - Unrestricted File Upload in Form Framework

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-15305: 0.25% estimated exploitation activity in the next 30 days; percentile 16.99 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

31 Aug 2026, 19:53 UTC

Last modified by the source

31 Aug 2026, 20:25 UTC

Source last checked

26 Oct 2026, 14:50 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mfqj-cqv3-h7xw

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mfqj-cqv3-h7xw

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# Patch Next advisory brief: CVE-2026-15305

Advisory: TYPO3 CMS - Unrestricted File Upload in Form Framework
IDs: CVE-2026-15305, GHSA-mfqj-cqv3-h7xw
Record: https://patchnext.com/advisories/cve-2026-15305 (revision 3, source checked 26 Oct 2026, 14:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: typo3/cms-form 14.3.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist typo3/cms-form: affected >= 14.2.0, <= 14.3.4; fixed in 14.3.5

## Suggested inspection (read-only)
- Packagist typo3/cms-form: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on typo3/cms-form.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-mfqj-cqv3-h7xw (OSV record GHSA-mfqj-cqv3-h7xw lists affected ranges: Packagist typo3/cms-form >=14.2.0 <14.3.5 (fixed))
- Verified: https://github.com/advisories/GHSA-mfqj-cqv3-h7xw (GitHub-reviewed advisory GHSA-mfqj-cqv3-h7xw lists affected ranges: Packagist typo3/cms-form >=14.2.0 <=14.3.4)

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