CVE-2025-59455: JetBrains TeamCity Race Condition Flaw

CVE-2025-59455 Overview

CVE-2025-59455 is a race condition vulnerability in JetBrains TeamCity that allows project isolation bypass. The flaw affects TeamCity versions before 2025.07.2 and stems from concurrent operations that fail to enforce proper isolation boundaries between projects. An authenticated attacker with low privileges can exploit the timing window to access resources across project scopes.

The issue is tracked under CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization. JetBrains addressed the vulnerability in TeamCity 2025.07.2.

Critical Impact
Authenticated users can bypass project isolation controls during a narrow race window, potentially exposing configuration data and build artifacts from other projects on the same TeamCity server.

Affected Products

JetBrains TeamCity versions before 2025.07.2
On-premises TeamCity server deployments
Multi-project TeamCity installations relying on project-level isolation

Discovery Timeline

2025-09-17 - CVE-2025-59455 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-59455

Vulnerability Analysis

TeamCity organizes builds, configurations, and permissions around a project hierarchy. Project isolation ensures that users granted access to one project cannot read or influence resources belonging to another. This vulnerability breaks that guarantee under concurrent access.

The defect arises when two or more operations touch shared project resources without adequate synchronization. During the race window, permission checks may reference state that no longer reflects the target resource, allowing operations to complete outside the intended project boundary. The result is limited disclosure or modification of data scoped to another project.

Exploitation requires network access to the TeamCity web interface and valid low-privilege credentials. Attack complexity is high because the attacker must reliably trigger the timing window, which reduces practical exploitability but does not eliminate risk in shared or multi-tenant environments.

Root Cause

The root cause is improper synchronization of a shared resource during concurrent execution [CWE-362]. Isolation logic performs authorization decisions and resource access as separate steps without atomic locking, creating a time-of-check to time-of-use gap that an attacker can race.

Attack Vector

The attacker authenticates to TeamCity with any valid account and issues concurrent requests targeting resources or endpoints that cross project boundaries. Timing the requests to overlap the vulnerable window causes the isolation check to pass against stale or partial state. Successful races yield limited read or write access to another project's data. No user interaction is required beyond the attacker's own session.

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

Detection Methods for CVE-2025-59455

Indicators of Compromise

Bursts of near-simultaneous API requests from a single authenticated user targeting different project IDs
Audit log entries showing a user accessing or modifying resources outside their assigned project scope
Unexpected changes to build configurations, parameters, or artifacts by accounts without prior activity in those projects

Detection Strategies

Baseline normal per-user API request rates against TeamCity endpoints and alert on concurrent request bursts that cross project boundaries.
Correlate TeamCity audit logs with authorization decisions to identify accesses that succeeded despite lacking explicit project permissions.
Review the running TeamCity server version against 2025.07.2 and flag any host still on a vulnerable build.

Monitoring Recommendations

Ingest TeamCity server, audit, and access logs into a centralized analytics platform for retention and correlation.
Track build configuration and parameter changes with change-management tooling to spot unauthorized modifications quickly.
Monitor authentication events for accounts exhibiting scanning patterns across multiple project IDs.

How to Mitigate CVE-2025-59455

Immediate Actions Required

Upgrade all TeamCity servers to version 2025.07.2 or later.
Rotate secrets, API tokens, and connection credentials stored in TeamCity if unauthorized cross-project activity is suspected.
Review project role assignments and remove unnecessary low-privilege accounts that could be used to launch the race.

Patch Information

JetBrains fixed CVE-2025-59455 in TeamCity 2025.07.2. Administrators should follow the standard upgrade procedure and review the JetBrains Security Issues Fixed advisory for the full list of resolved issues in this release.

Workarounds

Restrict network access to the TeamCity web interface to trusted administrative networks and CI runners.
Limit account creation and enforce strong authentication with multi-factor authentication for all users.
Segment sensitive projects onto separate TeamCity servers where shared-tenancy risk is unacceptable until patching is complete.

bash

# Verify TeamCity server version after upgrade
curl -s -u <user>:<token> https://teamcity.example.com/app/rest/server \
  | grep -oE 'version="[^"]+"'

# Expected: version="2025.07.2" or later