# CVE-2026-15305: TYPO3 CMS - Unrestricted File Upload in Form Framework

> Attackers can upload malicious files to TYPO3 forms if MIME type restrictions are configured, potentially leading to remote code execution.

- **Severity:** Medium 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Jul 2026
- **Updated:** 15 Jul 2026
- **Also known as:** GHSA-mfqj-cqv3-h7xw

## What is CVE-2026-15305?

CVE-2026-15305 is a medium-severity vulnerability in TYPO3 CMS, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-351 (Insufficient Type Distinction)

## Which versions are affected by CVE-2026-15305?

2 open source packages ship an affected version, including typo3/cms-form.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `typo3/cms-form` | Packagist | From 14.2.0 | 14.3.5 |
| `typo3/cms-form` | Packagist | From 14.2.0 | 14.3.5 |

## How do I fix CVE-2026-15305?

Upgrade typo3/cms-form to 14.3.5 or later.

## Is CVE-2026-15305 being exploited?

There is no known exploitation of CVE-2026-15305 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15305 and fix it if it is affected.

What it is: CVE-2026-15305 is a medium-severity vulnerability in TYPO3 CMS, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-15305 in the wild and no public exploit code.

Affected packages and fixed versions:
- typo3/cms-form (Packagist): affected from 14.2.0; fixed in 14.3.5
- typo3/cms-form (Packagist): affected from 14.2.0; fixed in 14.3.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-15305/ (Markdown: https://insights.sbomify.com/CVE-2026-15305/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15305
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15305
- OSV: https://osv.dev/vulnerability/CVE-2026-15305

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15305/
Summaries are generated and may contain mistakes; the official description above is the record.