CVE-2025-59020 is an authorization bypass vulnerability classified under CWE-863, discovered in the TYPO3 CMS platform. The flaw arises from improper enforcement of field-level access controls when processing the defVals parameter during record creation in the TYPO3 backend interface. Specifically, users who have write permissions limited to certain fields in a database table can exploit this vulnerability to insert arbitrary data into exclude fields that should be inaccessible to them. This occurs because the system fails to correctly validate or restrict the defVals parameter, allowing attackers to circumvent intended access restrictions. The affected TYPO3 CMS versions span from 10.0.0 to 14.0.1, covering multiple major releases. The vulnerability requires an attacker to have network access and at least low-level write privileges but does not require user interaction or elevated privileges beyond those limited write rights. The impact primarily affects data integrity and confidentiality, as unauthorized data can be inserted or manipulated in sensitive fields. The CVSS 4.0 score of 5.3 reflects a medium severity, considering the ease of exploitation (low complexity), the requirement of limited privileges, and the absence of user interaction. No public exploits or active exploitation campaigns have been reported to date. The lack of patch links suggests that fixes may be pending or available through TYPO3 updates. Organizations relying on TYPO3 CMS for content management should assess their exposure and apply vendor updates or mitigations promptly to prevent unauthorized data manipulation.

For European organizations, this vulnerability poses a risk of unauthorized data manipulation within TYPO3 CMS-managed websites or applications. Attackers with limited write access could inject arbitrary data into restricted fields, potentially leading to data integrity issues, unauthorized content changes, or exposure of sensitive information stored in exclude fields. This could undermine trust in web services, damage organizational reputation, and lead to compliance violations under regulations such as GDPR if personal or sensitive data is affected. Since TYPO3 is widely used by public sector entities, educational institutions, and enterprises across Europe, exploitation could disrupt critical web services or lead to data leakage. The medium severity score indicates moderate risk, but the broad version range affected and the common use of TYPO3 in Europe elevate the threat. The absence of known exploits reduces immediate risk but does not preclude future attacks. Organizations with multi-tenant or role-based access control configurations in TYPO3 are particularly vulnerable if write permissions are not tightly controlled.

1. Immediately review and restrict write permissions in TYPO3 backend to the minimum necessary, ensuring users cannot write to sensitive or exclude fields. 2. Apply the latest TYPO3 CMS security updates as soon as they become available, as vendor patches are expected to address this vulnerability. 3. Implement strict input validation and sanitization on the defVals parameter if custom extensions or integrations handle it. 4. Conduct thorough audits of backend user roles and permissions to detect and remediate any over-privileged accounts. 5. Monitor TYPO3 CMS logs for unusual record creation activities or attempts to manipulate exclude fields. 6. Consider deploying Web Application Firewalls (WAF) with custom rules to detect and block suspicious defVals parameter usage. 7. Educate administrators and developers about the risks of field-level access bypass and enforce secure coding practices. 8. For critical environments, isolate TYPO3 backend access to trusted networks or VPNs to reduce exposure. 9. Regularly back up TYPO3 databases and content to enable recovery from unauthorized changes. 10. Engage with TYPO3 community and security advisories to stay informed about patches and exploit developments.