CVE-2025-41421 is a medium-severity vulnerability affecting the TeamViewer Full Client and Host for Windows versions prior to 15.70. The issue stems from improper handling of symbolic links (symlinks) during file access operations, specifically related to the update file path. This vulnerability is classified under CWE-59, which involves improper link resolution before file access, commonly referred to as 'link following'. An attacker with local, unprivileged access to a device that lacks adequate malware protection can exploit this flaw by creating a malicious symbolic link that redirects the update process to an attacker-controlled file path. This can lead to privilege escalation, allowing the attacker to gain unauthorized access to sensitive information. The vulnerability requires local access and a high attack complexity, with no user interaction needed. The CVSS v3.1 base score is 4.7, reflecting a medium severity primarily due to the requirement for local access and the complexity of the attack. The vulnerability does not impact integrity or availability directly but compromises confidentiality by potentially exposing sensitive data through unauthorized access. No known exploits are currently reported in the wild, and no official patches are linked yet, though versions 15.70 and later are not affected, implying that the issue has been addressed in those releases.

For European organizations, this vulnerability poses a risk primarily in environments where TeamViewer is used extensively for remote support and management, especially on Windows endpoints. Since exploitation requires local access and the absence of adequate malware protection, the threat is more significant in organizations with less stringent endpoint security controls or where insider threats or compromised local accounts are possible. Successful exploitation could lead to unauthorized access to sensitive corporate data, potentially including credentials, internal communications, or proprietary information. This could facilitate further lateral movement within networks or data exfiltration. The impact is heightened in sectors with strict data protection regulations such as GDPR, where unauthorized data access can lead to regulatory penalties and reputational damage. Additionally, organizations relying on TeamViewer for critical remote operations may face operational risks if attackers leverage this vulnerability to gain footholds in their systems.

European organizations should prioritize upgrading TeamViewer Full Client and Host installations to version 15.70 or later, where this vulnerability is resolved. Until upgrades are fully deployed, organizations should enforce strict local access controls, ensuring that only trusted users have local login capabilities on devices running vulnerable versions. Endpoint protection solutions should be enhanced to detect and block suspicious symbolic link creation or manipulation activities. Implementing application whitelisting and monitoring file system changes related to update paths can provide additional layers of defense. Regular auditing of local user accounts and privilege assignments will reduce the risk of unauthorized local access. Network segmentation can limit the spread of an attacker who gains local access. Finally, organizations should maintain up-to-date incident response plans to quickly identify and remediate any exploitation attempts.