JetBrains TeamCity CVE-2026-63077 Actively Exploited in the Wild, JPCERT Urges Immediate Patching and Breach Investigation
JetBrains has released security updates for its continuous integration product TeamCity after a critical vulnerability CVE-2026-63077 was found to be actively exploited in the wild.
The issue stems from unsafe deserialization of untrusted data via the agent polling protocol, enabling remote attackers to execute arbitrary code without authentication. JetBrains received the private report on July 10, 2026, and disclosed the flaw on July 27, shipping fixes in TeamCity 2026.1.3 and 2025.11.7.
Exploitation activity was subsequently observed, leading the U.S. Cybersecurity and Infrastructure Security Agency (CISA) to add the vulnerability to its Known Exploited Vulnerabilities Catalog on August 5 and require federal agencies to apply mitigations by August 8. JetBrains issued its own exploitation advisory on August 7.
The JPCERT Coordination Center confirmed that vulnerable versions of the on-premises TeamCity product are running in Japan. Public exploit code for the remote code execution flaw is now available, increasing the risk of further attacks.
JPCERT/CC strongly recommends that organizations immediately identify their deployed versions, apply the available patches without delay, and consider conducting forensic investigations for signs of compromise.
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