CISA has added CVE-2024-63077, a critical remote code execution vulnerability in JetBrains TeamCity, to its list of actively exploited flaws. The vulnerability carries a CVSS score of 9.8 and stems from insecure deserialization of untrusted data in on-premise TeamCity installations.

An unauthenticated attacker with network access to a TeamCity server can exploit this flaw to execute arbitrary code without requiring login credentials. JetBrains has released patches addressing the issue, but the vulnerability is already seeing real-world exploitation attempts.

TeamCity is widely deployed across development organizations for continuous integration and deployment workflows. On-premise instances are particularly at risk, as they typically operate within enterprise networks where attackers who gain initial access can pivot toward the deployment pipeline. Successful exploitation grants attackers code execution at the application level, potentially allowing them to modify build artifacts, inject malicious code into software releases, or harvest credentials from the CI/CD environment.

The active exploitation campaign signals that threat actors have functional exploit code and are actively targeting exposed TeamCity instances. Organizations running vulnerable versions should prioritize patching immediately. Network administrators should verify that TeamCity servers are not unnecessarily exposed to untrusted networks and implement access controls restricting connectivity to authorized networks only.

CISA's addition of this flaw to its Known Exploited Vulnerabilities catalog underscores the severity and real-world threat. Development teams and DevOps personnel should audit their TeamCity deployments, check version numbers against JetBrains' advisory, and apply patches without delay. Teams unable to patch immediately should restrict network access to TeamCity servers and monitor logs for suspicious activity patterns consistent with exploitation attempts.

The vulnerability's high CVSS rating and unauthenticated nature make it a top-priority remediation target for any organization running TeamCity on-