CVE-2025-46618 is a stored Cross-Site Scripting (XSS) vulnerability identified in JetBrains TeamCity, a widely used continuous integration and build management system. The vulnerability affects versions of TeamCity prior to 2025.03.1 and specifically targets the Data Directory tab within the application. Stored XSS (CWE-79) occurs when malicious scripts are injected into a web application and then permanently stored on the server, later executed in the browsers of users who access the affected content. In this case, the vulnerability allows an attacker to inject malicious JavaScript code into the Data Directory tab, which is then rendered and executed in the context of the TeamCity web interface. This can lead to session hijacking, unauthorized actions on behalf of legitimate users, theft of sensitive information, or further exploitation of the internal network. The vulnerability does not require user interaction beyond visiting the affected page, and authentication is typically required to access the TeamCity interface, meaning the attacker must have some level of access to the system to exploit this flaw. No public exploits are currently known in the wild, and no official patches have been linked yet, though JetBrains has reserved the CVE and presumably will release a fix. The vulnerability is classified as medium severity, reflecting the moderate impact and the requirement for authentication. However, given TeamCity’s role in software development pipelines, exploitation could have significant downstream effects if leveraged to compromise build processes or inject malicious code into software artifacts.

For European organizations, the impact of this vulnerability can be significant, especially for those relying heavily on TeamCity for continuous integration and deployment. Exploitation could allow attackers to execute arbitrary scripts within the TeamCity web interface, potentially leading to credential theft, unauthorized access to build configurations, and manipulation of build artifacts. This could compromise the integrity of software development pipelines, leading to the distribution of malicious code or disruption of development workflows. Confidentiality could be impacted if sensitive project data or credentials are exposed. Integrity is at risk due to the possibility of tampering with build processes. Availability impact is limited but possible if attackers disrupt the CI/CD environment. Since TeamCity is often used internally, exploitation could facilitate lateral movement within corporate networks, increasing the risk of broader compromise. The medium severity rating suggests a moderate but non-trivial risk, particularly in environments where access controls are lax or where TeamCity is exposed beyond internal networks.

1. Immediate mitigation should include restricting access to the TeamCity web interface to trusted users and networks only, using network segmentation and VPNs where possible. 2. Implement strict input validation and output encoding on the Data Directory tab to prevent injection of malicious scripts; while awaiting an official patch, administrators can review and sanitize any user-generated content or configuration entries related to this tab. 3. Monitor TeamCity logs for unusual activity or unexpected script injections. 4. Enforce strong authentication and role-based access controls to limit the number of users who can access or modify the Data Directory tab. 5. Regularly back up TeamCity configurations and build artifacts to enable recovery in case of compromise. 6. Stay alert for official patches from JetBrains and apply them promptly once available. 7. Consider deploying web application firewalls (WAFs) with rules tailored to detect and block XSS payloads targeting TeamCity. 8. Educate development and operations teams about the risks of XSS and the importance of secure coding and configuration practices within CI/CD tools.