CVE-2025-54534 in TeamCity
Summary
by MITRE • 07/28/2025
In JetBrains TeamCity before 2025.07 reflected XSS was possible on the agentpushPreset page
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Analysis
by VulDB Data Team • 07/31/2025
The vulnerability identified as CVE-2025-54534 represents a reflected cross-site scripting flaw discovered in JetBrains TeamCity prior to version 2025.07. This security weakness resides within the agentpushPreset page functionality of the TeamCity continuous integration and deployment platform. The issue arises from insufficient input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before incorporating it into web responses. The reflected nature of this vulnerability indicates that malicious actors can craft specially crafted URLs containing malicious script payloads that are then reflected back to users who click on these links, typically through social engineering tactics or phishing campaigns. This particular vulnerability affects the agentpushPreset page which is used for managing agent push presets in TeamCity's distributed build infrastructure, making it a potentially critical vector for attackers seeking to compromise the CI/CD environment.
The technical exploitation of this vulnerability occurs when an attacker constructs a malicious URL containing script code within parameters that are processed by the agentpushPreset page. When a victim user accesses this crafted URL, the malicious script code becomes embedded in the page response and executes within the victim's browser context. This execution can occur without any server-side interaction, as the script is reflected directly from the user input back to the browser. The vulnerability specifically impacts the handling of input parameters that are used to configure agent push presets, which are critical components in TeamCity's build agent management system. The flaw stems from improper sanitization of user-provided data, allowing HTML and JavaScript code to be interpreted as part of the web page content rather than as plain text or escaped data. According to CWE classification, this vulnerability maps to CWE-79 which describes "Cross-site Scripting" and specifically addresses the reflected variant of this attack pattern. The ATT&CK framework categorizes this under TA0001 (Initial Access) and TA0002 (Execution) tactics, where attackers leverage web-based vulnerabilities to establish initial access and subsequently execute malicious code within the victim's browser environment.
The operational impact of CVE-2025-54534 extends beyond simple script execution as it provides attackers with a potential foothold for more sophisticated attacks within the TeamCity environment. An attacker who successfully exploits this vulnerability can potentially steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users within the TeamCity application. The agentpushPreset page functionality is particularly valuable to attackers because it can be used to manipulate build agent configurations, potentially leading to unauthorized access to build resources or execution of malicious build scripts. This vulnerability is especially concerning in enterprise environments where TeamCity serves as a central component of continuous integration and deployment pipelines, as it could enable attackers to compromise the entire CI/CD infrastructure. The reflected nature of the vulnerability means that exploitation requires user interaction, but the potential for widespread impact increases when considering that TeamCity is often used in collaborative environments where users frequently click on links shared via email or messaging platforms. The vulnerability also poses risks to the integrity of build processes and could potentially be leveraged to inject malicious code into build artifacts, affecting the security posture of applications deployed through these pipelines.
The recommended mitigation strategy for CVE-2025-54534 involves immediate upgrading to JetBrains TeamCity version 2025.07 or later, which contains the necessary patches to address the reflected XSS vulnerability. Organizations should also implement additional security measures including input validation and output encoding mechanisms that properly sanitize all user-supplied data before it is rendered in web responses. Security teams should conduct comprehensive vulnerability assessments to identify any other potentially affected pages or components within the TeamCity installation that might share similar input handling patterns. The implementation of Content Security Policy (CSP) headers can provide an additional layer of protection against XSS attacks by restricting the sources from which scripts can be loaded and executed. Network-level protections such as web application firewalls and intrusion detection systems should be configured to monitor for suspicious patterns associated with XSS attack attempts. Regular security training for developers and administrators regarding secure coding practices and the importance of input validation can help prevent similar vulnerabilities from being introduced in future releases. Organizations should also establish robust monitoring procedures to detect and respond to potential exploitation attempts, including logging and alerting on suspicious user activities related to the agentpushPreset functionality and other potentially vulnerable components within the TeamCity platform.