CVE-2026-103494: JetBrains YouTrack Privilege Escalation

CVE-2026-103494 Overview

CVE-2026-103494 is a privilege escalation vulnerability in JetBrains YouTrack versions prior to 2026.2.19422. The flaw allows an authenticated attacker with high privileges to escalate access through user group membership changes. The vulnerability is classified under [CWE-266] Incorrect Privilege Assignment. JetBrains addressed the issue in YouTrack release 2026.2.19422.

Critical Impact
Successful exploitation grants unauthorized access to projects, issues, and administrative functions within YouTrack, compromising confidentiality, integrity, and availability of hosted project data.

Affected Products

JetBrains YouTrack versions before 2026.2.19422
Self-hosted YouTrack Server deployments
YouTrack instances exposed to authenticated users with group management capabilities

Discovery Timeline

2026-10-01 - CVE-2026-103494 published to NVD
2026-10-02 - Last updated in NVD database

Technical Details for CVE-2026-103494

Vulnerability Analysis

The vulnerability resides in YouTrack's user group management functionality. An attacker with existing elevated privileges can manipulate group membership assignments to grant themselves or other accounts permissions beyond their authorized scope. The flaw affects access control enforcement during group membership modifications.

YouTrack uses group-based permission inheritance to assign roles and project access. When membership changes bypass proper authorization checks, attackers acquire permissions tied to higher-privilege groups. This breaks the project's role-based access control (RBAC) model and allows lateral movement within the YouTrack tenant.

The attack is network-accessible but requires high privileges and increased attack complexity, limiting opportunistic exploitation. The exploit prediction scoring indicates low near-term exploitation likelihood, though insider-threat scenarios remain plausible.

Root Cause

The root cause is incorrect privilege assignment [CWE-266] during user group membership operations. YouTrack's authorization layer did not sufficiently validate the resulting effective permissions when group memberships were modified, enabling escalation beyond the attacker's assigned role.

Attack Vector

An authenticated attacker with group management rights submits membership changes that add their account, or a controlled account, to a higher-privilege group. The server applies the change without enforcing the authorization boundary, granting the elevated permissions. Attackers then access restricted projects, modify issue data, or perform administrative actions.

No verified public exploit code is available. See the JetBrains Security Issues Fixed advisory for vendor-published details.

Detection Methods for CVE-2026-103494

Indicators of Compromise

Unexpected group membership modifications in YouTrack audit logs, particularly additions to administrator or project-admin groups
User accounts gaining access to projects outside their documented role scope
API calls to group management endpoints originating from accounts without historical administrative activity

Detection Strategies

Review YouTrack audit logs for group membership change events and correlate against change-management records
Baseline authorized administrators and alert on membership changes performed by non-baseline accounts
Monitor REST API calls to /api/groups and user management endpoints for anomalous patterns

Monitoring Recommendations

Forward YouTrack application and audit logs to a centralized SIEM for correlation and retention
Alert on privilege-sensitive actions such as role assignments, group creation, and administrator additions
Track authentication events for accounts that recently acquired elevated group memberships

How to Mitigate CVE-2026-103494

Immediate Actions Required

Upgrade all YouTrack installations to version 2026.2.19422 or later without delay
Audit current group memberships and remove accounts that should not hold administrative privileges
Rotate credentials and session tokens for accounts with group management permissions
Review audit logs since the last known-good state for unauthorized membership modifications

Patch Information

JetBrains released the fix in YouTrack 2026.2.19422. Administrators of self-hosted deployments should apply the patched release following the vendor's upgrade procedure. Refer to the JetBrains Security Issues Fixed page for the complete advisory.

Workarounds

Restrict group management permissions to a minimal set of trusted administrators until patching is complete
Enforce multi-factor authentication for all accounts with user or group administration rights
Place YouTrack behind authenticated network controls or VPN to reduce exposure of management endpoints

bash

# Verify YouTrack version post-upgrade
curl -s -H "Authorization: Bearer <token>" \
  https://youtrack.example.com/api/config?fields=version

# Expected output should report version 2026.2.19422 or later