CISA Flags TeamCity CVE-2026-63077 RCE Flaw Under Active Exploitation in the Wild - The Hacker News

A newly patched security flaw impacting on-premise versions of JetBrains TeamCity has come under active exploitation in the wild, according to the U.S. Cybersecurity and Infrastructure Security Agency (CISA).

The vulnerability in question is CVE-2026-63077 (CVSS score: 9.8), a case of deserialization of untrusted data that could allow an unauthenticated attacker with access to a TeamCity server to bypass authentication checks and execute arbitrary operating system commands with the privileges of the TeamCity server process.

"JetBrains TeamCity contains a deserialization of untrusted data vulnerability that could allow unauthenticated remote code execution via the agent polling protocol," CISA said.

According to JetBrains, the vulnerability can be exploited by an unauthenticated attacker via the TeamCity agent polling protocol to sidestep authentication checks and execute arbitrary operating system commands.