CVE-2025-59020
📋 TL;DR
This vulnerability allows authenticated TYPO3 backend users with write permissions to bypass field-level access controls during record creation. By exploiting the defVals parameter, attackers can insert arbitrary data into prohibited exclude fields they shouldn't have access to. This affects TYPO3 CMS installations running vulnerable versions.
💻 Affected Systems
- TYPO3 CMS
📦 What is this software?
Typo3 by Typo3
Typo3 by Typo3
Typo3 by Typo3
Typo3 by Typo3
Typo3 by Typo3
⚠️ Risk & Real-World Impact
Worst Case
Attackers with backend access could manipulate sensitive database fields, potentially compromising data integrity, escalating privileges, or modifying critical system configurations.
Likely Case
Authenticated users exploiting this vulnerability to modify data in fields they shouldn't have access to, potentially leading to data manipulation or privilege escalation within the CMS.
If Mitigated
With proper access controls and field validation, impact is limited to authorized users manipulating data within their permitted scope.
🎯 Exploit Status
Exploitation requires authenticated backend access and knowledge of the vulnerable parameter. The vulnerability is in access control logic rather than a complex technical flaw.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: TYPO3 v10.4.55, v11.5.49, v12.4.41, v13.4.23, v14.0.2
Vendor Advisory: https://typo3.org/security/advisory/typo3-core-sa-2026-001
Restart Required: No
Instructions:
1. Identify your TYPO3 version. 2. Update to the patched version for your branch. 3. Clear TYPO3 caches. 4. Verify the update was successful.
🔧 Temporary Workarounds
Restrict backend access
allLimit backend access to trusted users only and implement strong authentication controls.
Review user permissions
allAudit and minimize backend user write permissions to only necessary fields.
🧯 If You Can't Patch
- Implement strict access controls and monitor backend user activities
- Consider using a web application firewall (WAF) to detect and block suspicious parameter manipulation
🔍 How to Verify
Check if Vulnerable:
Check your TYPO3 version against affected ranges in the admin panel or via composer show typo3/cms-core.Check Version:
composer show typo3/cms-core | grep versionVerify Fix Applied:
Verify your TYPO3 version is equal to or higher than the patched versions: 10.4.55, 11.5.49, 12.4.41, 13.4.23, or 14.0.2.📡 Detection & Monitoring
Log Indicators:
- Unusual backend user activity with defVals parameter
- Multiple failed access attempts to restricted fields
Network Indicators:
- HTTP POST requests to TYPO3 backend with defVals parameter containing unexpected field names
SIEM Query:
source="typo3.log" AND (defVals OR "access check" OR "field bypass")