CVE-2026-63077
Prioritize patching. It under exploitation confirmed by CISA and has a public proof of concept.
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
An unauthenticated attacker can execute arbitrary code remotely on JetBrains TeamCity servers through the agent polling protocol. This is a critical vulnerability because it requires no login credentials and allows complete system compromise.
The vulnerability exists in the agent polling protocol of TeamCity versions before 2026.1.3 and 2025.11.7, allowing unauthenticated remote code execution via deserialization of untrusted data (CWE-502). An attacker with network access to the polling endpoint can craft malicious serialized objects to execute arbitrary code with the privileges of the TeamCity service.