CVE-2025-48200 is a critical security vulnerability identified in the sr_feuser_register extension version 5.1.0 for the TYPO3 content management system. This vulnerability is classified under CWE-502, which pertains to the deserialization of untrusted data. The sr_feuser_register extension is commonly used to manage frontend user registrations in TYPO3 websites. The flaw allows an unauthenticated remote attacker to execute arbitrary code on the affected system by exploiting unsafe deserialization processes within the extension. Specifically, the vulnerability arises when the extension processes serialized data from untrusted sources without proper validation or sanitization, enabling the attacker to craft malicious serialized payloads that, when deserialized, trigger remote code execution (RCE). The CVSS v3.1 base score is 10.0, indicating a critical severity with the vector AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H, meaning the attack can be performed remotely over the network without any privileges or user interaction, and it results in complete compromise of confidentiality, integrity, and availability. No patches or mitigations are currently linked, and no known exploits have been reported in the wild as of the publication date (May 21, 2025). Given the nature of TYPO3 as a widely used CMS in Europe, this vulnerability poses a significant risk to websites relying on this extension for user registration functionality.

For European organizations, especially those operating websites or web applications built on TYPO3 using the sr_feuser_register extension, this vulnerability represents a severe threat. Successful exploitation can lead to full system compromise, including unauthorized access to sensitive data, defacement of websites, deployment of malware, or use of the compromised server as a pivot point for further attacks within the network. This can result in data breaches violating GDPR regulations, financial losses, reputational damage, and operational disruptions. Public sector entities, educational institutions, and enterprises using TYPO3 are particularly at risk due to the extension's role in managing user registrations, which often involves handling personal data. The lack of required authentication and user interaction lowers the barrier for attackers, increasing the likelihood of exploitation if the vulnerable extension is exposed to the internet. Additionally, the critical severity score underscores the urgency for European organizations to assess their TYPO3 deployments and take immediate action to mitigate potential exploitation.

1. Immediate audit of TYPO3 installations to identify the presence and version of the sr_feuser_register extension. 2. Disable or remove the sr_feuser_register extension version 5.1.0 until a secure patch or update is available. 3. Implement strict input validation and sanitization on all serialized data inputs if custom modifications exist. 4. Employ web application firewalls (WAFs) with rules designed to detect and block malicious serialized payloads targeting TYPO3 extensions. 5. Restrict public access to the user registration endpoints where feasible, using IP whitelisting or CAPTCHA mechanisms to reduce automated exploitation attempts. 6. Monitor logs for unusual deserialization activities or unexpected code execution patterns. 7. Stay updated with TYPO3 security advisories for the release of patches or mitigations addressing this vulnerability. 8. Consider isolating TYPO3 instances in segmented network zones to limit lateral movement in case of compromise.