CVE-2026-25846 is a vulnerability identified in JetBrains YouTrack, a popular issue tracking and project management tool used by software development teams worldwide. The flaw exists in versions prior to 2025.3.119033 and involves the inadvertent exposure of access tokens within mailbox logs. This vulnerability is classified under CWE-532, which pertains to the exposure of sensitive information in logs. Access tokens are critical credentials that grant access to YouTrack resources and APIs; their exposure can lead to unauthorized access if intercepted by malicious actors. The vulnerability requires an attacker to have network access and low privileges (PR:L) but does not require user interaction (UI:N), making exploitation feasible in environments where attackers can monitor or access mailbox logs. The CVSS 3.1 base score is 6.5, indicating a medium severity level, with the vector AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N highlighting that the attack is network-based, with low complexity, requires privileges, no user interaction, unchanged scope, high confidentiality impact, and no impact on integrity or availability. No public exploits have been reported yet, but the risk remains significant due to the sensitive nature of access tokens. The vulnerability underscores the importance of secure logging practices, especially for sensitive authentication tokens, to prevent leakage through logs that may be accessible to unauthorized users or systems.

For European organizations, the exposure of access tokens in YouTrack mailbox logs can lead to unauthorized access to project management and issue tracking data, potentially compromising sensitive project information, intellectual property, and internal workflows. While the vulnerability does not directly affect system integrity or availability, the confidentiality breach can facilitate lateral movement within networks or unauthorized API usage, increasing the risk of further compromise. Organizations with extensive software development operations relying on YouTrack are particularly at risk, as attackers could leverage stolen tokens to manipulate issue tracking data or access confidential project details. The impact is heightened in regulated industries such as finance, healthcare, and critical infrastructure sectors prevalent in Europe, where data confidentiality is paramount. Additionally, the exposure of tokens could violate data protection regulations like GDPR if personal or sensitive data is indirectly accessed or disclosed. The lack of known exploits reduces immediate risk but does not eliminate the threat, especially given the medium CVSS score and ease of exploitation.

European organizations should immediately upgrade JetBrains YouTrack to version 2025.3.119033 or later, where this vulnerability is addressed. Until patching is complete, organizations should audit mailbox logs to identify and remove any exposed access tokens and restrict access to these logs to only trusted administrators. Implement strict access controls and monitoring on systems storing or processing YouTrack logs to detect unauthorized access attempts. Consider rotating access tokens that may have been exposed to invalidate compromised credentials. Additionally, review and enhance logging configurations to exclude sensitive information such as tokens from logs or use secure logging mechanisms that encrypt sensitive data. Network segmentation can limit attacker access to mailbox logs, reducing exploitation risk. Finally, educate development and operations teams on secure handling of authentication tokens and the importance of minimizing sensitive data exposure in logs.