CVE-2026-86492: JetBrains YouTrack Information Disclosure

CVE-2026-86492 Overview

CVE-2026-86492 affects JetBrains YouTrack versions prior to 2026.2.18634. A shared token cache implementation allowed cross-tenant theft of GitHub App installation tokens. Authenticated users in one tenant could retrieve installation tokens belonging to GitHub App integrations configured by other tenants. This weakness is classified under [CWE-488] (Exposure of Data Element to Wrong Session). JetBrains addressed the issue in YouTrack 2026.2.18634.

Critical Impact
Attackers with low-privilege access to a YouTrack tenant could steal GitHub App installation tokens from other tenants, enabling unauthorized access to connected GitHub repositories and code.

Affected Products

JetBrains YouTrack versions prior to 2026.2.18634
YouTrack deployments integrated with GitHub Apps
Multi-tenant YouTrack environments sharing the vulnerable token cache

Discovery Timeline

2026-09-07 - CVE-2026-86492 published to the National Vulnerability Database (NVD)
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-86492

Vulnerability Analysis

The vulnerability resides in the token caching layer that YouTrack uses to store GitHub App installation tokens. Installation tokens are short-lived credentials that GitHub Apps use to act on behalf of a specific installation. YouTrack cached these tokens in a structure that was not properly scoped to a single tenant. As a result, authenticated users belonging to one tenant could receive tokens generated for a different tenant. This bypasses the tenant isolation model that multi-tenant deployments rely on.

Root Cause

The root cause is a shared session data element ([CWE-488]) in the cache used to store GitHub App installation tokens. The cache keying strategy did not incorporate a tenant identifier, so cache lookups could return tokens issued for other tenants. This class of defect commonly occurs when a caching layer is added for performance without preserving the original authorization boundaries.

Attack Vector

An attacker requires low-privilege authenticated access to a YouTrack instance that hosts multiple tenants and has GitHub App integrations configured. The attacker performs actions that trigger token retrieval from the shared cache. When the cache returns a token belonging to a different tenant, the attacker can extract it and use it against the GitHub API. Because the scope changes from YouTrack to GitHub, the attack has confidentiality impact on connected source code repositories.

No verified public exploit code is available. See the JetBrains Fixed Security Issues advisory for vendor-supplied technical context.

Detection Methods for CVE-2026-86492

Indicators of Compromise

Unexpected GitHub API calls originating from YouTrack service accounts or IP ranges outside normal integration patterns
GitHub audit log entries showing repository access by installation tokens from tenants that did not initiate the action
Anomalous clone, pull, or read operations against private repositories tied to GitHub App installations
YouTrack access logs showing users requesting integration endpoints outside their assigned tenant context

Detection Strategies

Correlate YouTrack integration activity with GitHub App installation token usage to identify cross-tenant mismatches
Baseline normal GitHub App installation token consumption per tenant and alert on deviations
Inspect YouTrack application logs for repeated integration token retrieval calls from low-privilege accounts

Monitoring Recommendations

Ingest YouTrack audit logs and GitHub audit logs into a centralized SIEM for cross-source correlation
Alert on GitHub App installation token usage from unexpected source IPs or user agents
Monitor for repository access events that do not map to a known workflow, pipeline, or issue linkage in YouTrack

How to Mitigate CVE-2026-86492

Immediate Actions Required

Upgrade JetBrains YouTrack to version 2026.2.18634 or later without delay
Rotate all GitHub App installation credentials, private keys, and webhook secrets used by affected YouTrack integrations
Review GitHub audit logs for the period the vulnerable version was in use and investigate any anomalous repository access
Inventory all tenants with GitHub App integrations and validate that their token usage matches expected activity

Patch Information

JetBrains fixed the shared token cache issue in YouTrack 2026.2.18634. Administrators should apply the update following standard JetBrains upgrade procedures. Refer to the JetBrains Fixed Security Issues page for the authoritative advisory and release notes.

Workarounds

Temporarily disable GitHub App integrations in multi-tenant YouTrack deployments until the patched version is installed
Restrict GitHub App installation permissions to the minimum required scopes to limit blast radius if tokens are exposed
Segment tenants onto separate YouTrack instances where feasible to eliminate the shared cache exposure
Restrict network egress from YouTrack to the GitHub API and log all outbound integration traffic for review

bash

# Configuration example
# Verify the running YouTrack version after upgrade
curl -s -H "Authorization: Bearer <admin_token>" \
  https://<youtrack-host>/api/config | jq '.version'

# Expected output: "2026.2.18634" or later