Critical Vulnerability in JetBrains TeamCity Allows Unauthenticated Remote Code Execution
JetBrains has addressed a critical vulnerability in its TeamCity CI/CD server that enables unauthenticated remote code execution on affected on-premises installations.
The flaw, identified as CVE-2026-63077, resides in the product’s agent polling protocol. Attackers who can reach the TeamCity Server over HTTP or HTTPS can bypass authentication checks and execute arbitrary operating-system commands.
Depending on the privileges assigned to the server process, successful exploitation may result in leakage of stored data, configuration files, and credentials. Attackers could also alter server state or undermine the integrity of build artifacts and downstream CI/CD pipelines.
The vulnerability received a CVSSv3.1 base score of 9.8 and was rated Critical, the highest severity level. At the time the advisory was published, no exploitation attempts had been observed in the wild.
JetBrains released patched versions TeamCity 2026.1.3 and TeamCity 2025.11.7. A patch plugin is also available for all supported releases from TeamCity 2017.1 onward. Organizations unable to apply updates immediately are advised to restrict external network access to the server as a temporary mitigation.
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