CVE-2021-31777 is a SQL Injection vulnerability affecting the Dynamic Content Element (dce) extension versions 2.2.0 through 2.6.x prior to 2.6.2, and 2.7.x prior to 2.7.1, used within the TYPO3 content management system (CMS). TYPO3 is a widely used open-source CMS, particularly popular in Europe for enterprise and governmental websites. The vulnerability allows an attacker with backend user account access to execute arbitrary SQL commands against the underlying database. This occurs because the dce extension fails to properly sanitize or parameterize user input before incorporating it into SQL queries. Exploiting this flaw could enable an attacker to read, modify, or delete sensitive data stored in the database, potentially compromising the confidentiality and integrity of the CMS content and user data. Since exploitation requires a backend user account, the attacker must already have some level of authenticated access, which could be obtained through credential theft, phishing, or privilege escalation. No public exploits have been reported in the wild to date, and no CVSS score has been assigned. However, the vulnerability was publicly disclosed in April 2021, and patched versions 2.6.2 and 2.7.1 have been released to address the issue. The lack of a CVSS score suggests the need for a severity assessment based on impact and exploitability factors.

For European organizations using TYPO3 with the vulnerable dce extension, this vulnerability poses a significant risk. Successful exploitation could lead to unauthorized data access or manipulation, undermining the integrity of websites and potentially exposing sensitive customer or internal data. This is particularly critical for public sector entities, educational institutions, and enterprises relying on TYPO3 for content management. The requirement for backend user credentials limits the attack surface but does not eliminate risk, especially if credential management or access controls are weak. Compromise could result in defacement, data breaches, or further lateral movement within the network. Given TYPO3's strong presence in Europe, especially in Germany, the Netherlands, and other central European countries, the impact could be widespread if organizations do not promptly apply patches or mitigate the vulnerability.

Organizations should immediately upgrade the dce extension to version 2.6.2 or 2.7.1 or later, as these versions contain the necessary fixes. In addition, it is critical to audit and restrict backend user accounts to the minimum necessary privileges, enforce strong authentication mechanisms such as multi-factor authentication (MFA), and monitor backend access logs for suspicious activity. Regularly reviewing and rotating credentials can reduce the risk of compromised accounts. Implementing web application firewalls (WAFs) with SQL injection detection rules can provide an additional layer of defense. Conducting security assessments and penetration testing focused on backend access controls and input validation will help identify residual risks. Finally, organizations should maintain an up-to-date inventory of TYPO3 extensions and promptly apply security updates.