CVE-2026-25846: JetBrains YouTrack Info Disclosure Flaw

CVE-2026-25846 Overview

CVE-2026-25846 is an Information Leakage vulnerability affecting JetBrains YouTrack, a popular project management and issue tracking platform. The vulnerability allows access tokens to be exposed in Mailbox logs, potentially enabling attackers with log access to harvest authentication credentials and gain unauthorized access to YouTrack instances.

Critical Impact

Access tokens logged in plaintext could allow attackers to impersonate legitimate users, access sensitive project data, and potentially compromise connected integrations and services.

Affected Products

• JetBrains YouTrack versions before 2025.3.119033

Discovery Timeline

• 2026-02-09 - CVE CVE-2026-25846 published to NVD
• 2026-02-09 - Last updated in NVD database

Technical Details for CVE-2026-25846

Vulnerability Analysis

This vulnerability is classified under CWE-532 (Insertion of Sensitive Information into Log File), a common security weakness where applications inadvertently log sensitive data such as credentials, tokens, or personal information. In the context of YouTrack's Mailbox integration feature, access tokens are being written to log files without proper sanitization or redaction.

The vulnerability exists in YouTrack's email integration functionality, which processes incoming emails and manages mailbox connections. When the Mailbox feature processes authentication or connection events, the access tokens used for email server authentication are captured in the application logs. This creates a persistent record of sensitive credentials that could be accessed by administrators, support personnel, or attackers who gain access to the log storage systems.

Root Cause

The root cause of CVE-2026-25846 lies in insufficient logging hygiene within the Mailbox integration component of YouTrack. The application fails to properly sanitize or mask access tokens before writing log entries, violating the principle of never logging sensitive authentication material. This oversight likely occurred during development when verbose logging was enabled for debugging purposes and was not adequately reviewed before production release.

Attack Vector

An attacker can exploit this vulnerability through the following attack path:

1. Log Access Acquisition: The attacker gains access to YouTrack server logs through various means such as compromised administrator accounts, misconfigured log aggregation systems, backup files, or shared storage access
2. Token Extraction: By searching through Mailbox-related log entries, the attacker can identify and extract plaintext access tokens
3. Token Abuse: The extracted tokens can be used to authenticate as the legitimate user or service, potentially accessing email accounts, connected integrations, or escalating privileges within the YouTrack instance

The vulnerability requires low privileges to exploit, as log files are often accessible to system administrators, DevOps personnel, or through centralized logging solutions. No user interaction is required for exploitation once log access is obtained.

Detection Methods for CVE-2026-25846

Indicators of Compromise

• Unusual access patterns to YouTrack log files or log aggregation systems
• Authentication events from unexpected IP addresses using valid tokens
• Multiple concurrent sessions for the same user account from different locations
• Unexpected API activity using Mailbox-associated service accounts

Detection Strategies

• Implement log monitoring to detect access to YouTrack application logs by unauthorized users or systems
• Monitor for authentication anomalies where tokens are used from different geographic locations or IP addresses than expected
• Enable audit logging on log storage systems to track who accesses sensitive log files
• Deploy file integrity monitoring on YouTrack log directories to detect unauthorized access or exfiltration

Monitoring Recommendations

• Configure SentinelOne to monitor for suspicious process access to YouTrack log file paths
• Establish baseline authentication patterns and alert on deviations for Mailbox-related service accounts
• Implement centralized log management with access controls and audit trails
• Regularly review access permissions to log storage systems and revoke unnecessary access

How to Mitigate CVE-2026-25846

Immediate Actions Required

• Upgrade JetBrains YouTrack to version 2025.3.119033 or later immediately
• Rotate all access tokens associated with Mailbox integrations after upgrading
• Review existing log files for exposed tokens and securely delete or archive them
• Audit log access permissions and restrict to essential personnel only

Patch Information

JetBrains has addressed this vulnerability in YouTrack version 2025.3.119033. The patch implements proper token redaction in log output, ensuring sensitive authentication material is masked before being written to log files. Administrators should upgrade to this version or later to remediate the vulnerability. For detailed information about security fixes, refer to the JetBrains Security Issues Fixed page.

Workarounds

• If immediate patching is not possible, consider temporarily disabling the Mailbox integration feature until the upgrade can be completed
• Implement strict access controls on YouTrack log directories, limiting access to only essential system accounts
• Configure log rotation with short retention periods to minimize the exposure window of any logged tokens
• Encrypt log files at rest to add an additional layer of protection

# Restrict log file permissions (example for Linux systems)
chmod 640 /path/to/youtrack/logs/*.log
chown youtrack:youtrack-admins /path/to/youtrack/logs/*.log

# Rotate logs frequently to minimize exposure window
# Add to logrotate configuration
# /etc/logrotate.d/youtrack
# daily
# rotate 3
# compress
# delaycompress