CVE-2025-59456 is a path traversal vulnerability (CWE-23) identified in JetBrains TeamCity, a widely used continuous integration and build management system. This vulnerability affects versions of TeamCity prior to 2025.07.2 and occurs during the project archive upload process. Path traversal vulnerabilities allow an attacker to manipulate file paths to access directories and files outside the intended scope, potentially overwriting or reading arbitrary files on the server. In this case, the flaw arises because the application does not properly sanitize or validate the file paths during archive uploads, enabling an authenticated user with elevated privileges (PR:H) to craft malicious archive contents that traverse directories. The CVSS 3.1 base score is 5.5 (medium severity), with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), requiring high privileges (PR:H), no user interaction (UI:N), unchanged scope (S:U), no confidentiality impact (C:N), high integrity impact (I:H), and low availability impact (A:L). This means that while confidentiality is not directly affected, the attacker can modify critical files or configurations, potentially leading to system compromise or disruption of build processes. No known exploits are currently reported in the wild, and no official patches or mitigation links were provided at the time of publication. The vulnerability is significant because TeamCity is often integrated into enterprise development pipelines, and exploitation could allow attackers to tamper with build artifacts or inject malicious code into software releases.

For European organizations, the impact of this vulnerability can be substantial, especially for those relying on TeamCity for their software development lifecycle. Successful exploitation could lead to unauthorized modification of build configurations, insertion of malicious code into software artifacts, or disruption of continuous integration workflows. This can undermine software integrity, potentially leading to compromised applications being deployed in production environments. Given the medium CVSS score and the requirement for high privileges, the threat is more relevant to internal attackers or those who have already gained elevated access. However, the risk remains significant in environments where access controls are weak or where insider threats exist. The integrity of software supply chains is a critical concern in Europe, especially with increasing regulatory focus on software security and supply chain risk management. Disruption or tampering in build systems could have cascading effects on downstream applications and services, affecting confidentiality indirectly through trust erosion and potential secondary attacks.

European organizations should prioritize upgrading JetBrains TeamCity to version 2025.07.2 or later as soon as it becomes available to address this vulnerability. Until a patch is applied, organizations should enforce strict access controls limiting who can upload project archives, ensuring only trusted and authenticated users with the minimum necessary privileges have this capability. Implementing network segmentation to isolate build servers and monitoring file system changes on TeamCity servers can help detect suspicious activity. Additionally, validating and sanitizing inputs at the application layer, if possible through custom rules or plugins, can reduce risk. Organizations should also audit existing build artifacts and configurations for unauthorized changes and review logs for unusual upload patterns. Employing runtime application self-protection (RASP) or endpoint detection and response (EDR) solutions on build servers can provide additional layers of defense. Finally, integrating security into the DevOps pipeline by scanning build artifacts for integrity and anomalies can help detect exploitation attempts early.