Executive brief
JetBrains TeamCity, a popular platform for automating software builds and deployments, contains a critical security flaw in how it communicates with build agents. An attacker can exploit this vulnerability to gain full control over the TeamCity server without needing any login credentials. This could lead to the theft of proprietary source code, the injection of malicious code into software updates, or a complete shutdown of the development pipeline. This vulnerability is reportedly being actively exploited in the wild.
Technical details
A deserialization of untrusted data vulnerability (CWE-502) exists in JetBrains TeamCity within the agent polling protocol. The flaw allows an unauthenticated remote attacker to send specially crafted data to the server, which, when processed, results in arbitrary code execution with the privileges of the TeamCity service. The vulnerability is reachable over the network without user interaction. JetBrains has released patches in versions 2026.1.3 and 2025.11.7. This vulnerability has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation.
Affected products
- JetBrains TeamCity before 2026.1.3, 2025.11.7
Timeline
- 2026-07-27: disclosed
- 2026-07-27: patched: Fixed in versions 2026.1.3 and 2025.11.7
- 2026-08-05: kev added: Added to CISA KEV catalog due to active exploitation