Australian Cyber Security Centre warns of active TeamCity server exploitation

The Australian Cyber Security Centre (ACSC) has issued a high-severity alert regarding the active exploitation of a critical vulnerability in JetBrains' TeamCity On-Premises servers within Australia. The flaw, identified as CVE-2026-63077, is rated 9.8 out of 10 in severity.

An unauthenticated attacker with HTTP(S) access to a vulnerable server can bypass authentication checks to execute arbitrary operating system commands. This vulnerability poses a significant risk to continuous integration and continuous deployment (CI/CD) pipelines, as a successful attack could expose sensitive data, configurations, and stored credentials, or compromise the integrity of build artifacts.

The ACSC advises all Australian organisations using TeamCity On-Premises to review their environments, apply patches immediately, and monitor for suspicious activity. While no specific industry has been identified as a target, the agency recommends assessing whether TeamCity interfaces are unnecessarily exposed to the internet. Organisations using third-party managed services are also urged to confirm that patching and monitoring arrangements are in place.