CVE-2024-25121 is a high-severity vulnerability affecting multiple versions of TYPO3, an open-source PHP-based web content management system widely used for building and managing websites. The vulnerability arises from improper handling of File Abstraction Layer (FAL) entities via the DataHandler component. Specifically, attackers with valid backend user credentials can persist FAL entities directly, enabling them to reference files stored in the fallback storage (also known as "zero-storage"). This fallback storage is a backward compatibility layer for files located outside properly configured file storages and within the public web root directory. Exploiting this flaw allows unauthorized disclosure of sensitive file names and contents that should otherwise be protected. The vulnerability is rooted in CWE-200 (Exposure of Sensitive Information) and CWE-284 (Improper Access Control), indicating that the system fails to adequately restrict access to sensitive file data. The issue affects TYPO3 versions from 8.0.0 up to but not including the patched versions 8.7.57 ELTS, 9.5.46 ELTS, 10.4.43 ELTS, 11.5.35 LTS, 12.4.11 LTS, and 13.0.1. The fix involves denying direct persistence of sys_file entities by default and preventing sys_file_reference and sys_file_metadata entities from referencing files in fallback storage unless explicitly allowed during secure data imports. The CVSS 3.1 base score is 7.1, reflecting a high severity due to network attack vector, low attack complexity, required privileges (valid backend user), no user interaction, and high confidentiality impact with limited integrity impact and no availability impact. No known exploits are currently reported in the wild, but the vulnerability poses a significant risk to TYPO3 installations with exposed backend access.

For European organizations, especially those relying on TYPO3 for their web presence, this vulnerability could lead to unauthorized disclosure of sensitive files hosted on their web servers. Since the fallback storage may contain legacy or misconfigured files within the public web root, attackers with backend access could extract confidential information such as configuration files, private documents, or proprietary data. This exposure risks violating data protection regulations like GDPR, potentially resulting in legal penalties and reputational damage. The requirement for valid backend credentials somewhat limits the attack surface; however, compromised or weak backend accounts are common attack vectors. Organizations with large TYPO3 deployments, including government, education, and private sectors, could face targeted exploitation attempts. The integrity and availability of systems are less impacted, but confidentiality breaches could facilitate further attacks or data leaks. Given TYPO3's popularity in Europe, the vulnerability could affect a broad range of sectors, increasing the urgency for patching.

European organizations should immediately verify their TYPO3 versions and upgrade to the fixed releases: 8.7.57 ELTS, 9.5.46 ELTS, 10.4.43 ELTS, 11.5.35 LTS, 12.4.11 LTS, or 13.0.1. Beyond patching, organizations must audit backend user accounts to ensure strong authentication mechanisms, including enforcing multi-factor authentication (MFA) and reviewing user privileges to minimize access. Restrict backend access via network segmentation and VPNs to reduce exposure. Additionally, review file storage configurations to eliminate or properly secure fallback storage usage, ensuring sensitive files are not publicly accessible. Implement monitoring and alerting on unusual backend activity, especially related to DataHandler operations or file access patterns. For environments importing data from secure origins, ensure the DataHandler instance explicitly enables importing mode as per the patch guidance to avoid misconfigurations. Regularly conduct security assessments and penetration testing focused on backend access controls and file storage permissions to detect potential weaknesses.