CVE-2026-63077: JetBrains TeamCity remote code execution in agent polling protocol

CVE-2026-63077 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2026-07-27

JetBrains TeamCity, a popular platform for automating software builds and deployments, contains a critical security flaw in how it communicates with build agents. An attacker can exploit this vulnerability to gain full control over the TeamCity server without needing any login credentials. This could lead to the theft of proprietary source code, the injection of malicious code into software updates, or a complete shutdown of the development pipeline. This vulnerability is reportedly being actively exploited in the wild.

Technologies: Jetbrains TeamCity. Vendors: Jetbrains.

Quick answers

Is CVE-2026-63077 exploited in the wild?
Yes. CVE-2026-63077 is known to be exploited in the wild, first recorded on 5 August 2026. Treat it as urgent.
How severe is CVE-2026-63077?
Critical severity, with a CVSS score of 9.8, published 27 July 2026.
Which products and versions are affected?
Jetbrains TeamCity before 2026.1.3, 2025.11.7.
Is there a fix for CVE-2026-63077?
A patch was published on 2026-07-27: Fixed in versions 2026.1.3 and 2025.11.7 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-63077 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-63077?
Check whether you run Jetbrains TeamCity at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A deserialization of untrusted data vulnerability (CWE-502) exists in JetBrains TeamCity within the agent polling protocol. The flaw allows an unauthenticated remote attacker to send specially crafted data to the server, which, when processed, results in arbitrary code execution with the privileges of the TeamCity service. The vulnerability is reachable over the network without user interaction. JetBrains has released patches in versions 2026.1.3 and 2025.11.7. This vulnerability has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation.

Affected products

  • JetBrains TeamCity before 2026.1.3, 2025.11.7

Timeline

  • 2026-07-27: disclosed
  • 2026-07-27: patched: Fixed in versions 2026.1.3 and 2025.11.7
  • 2026-08-05: kev added: Added to CISA KEV catalog due to active exploitation

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