Jul 27, 2026 · ZeroDay Catalog
Critical Deserialization Vulnerability in JetBrains TeamCity
A critical deserialization vulnerability in JetBrains TeamCity has been disclosed, allowing potential command execution without authentication.
What changed
On July 27, 2026, JetBrains issued a security advisory regarding CVE-2026-63077, a critical vulnerability in TeamCity related to unsafe deserialization of untrusted data. This flaw allows attackers to exploit the agent polling protocol over HTTP or HTTPS, enabling them to execute operating system commands with the privileges of the TeamCity server process.
Who is affected
The vulnerability affects organizations using JetBrains TeamCity, particularly those with exposed servers accessible over the internet. Although JetBrains reported no known active exploitation at the time of disclosure, the situation changed when CISA added this vulnerability to its Known Exploited Vulnerabilities catalog on August 5, 2026.
- JetBrains TeamCity users with internet-facing servers.
- Organizations relying on CI/CD pipelines that utilize TeamCity.
- Development teams using JetBrains products in their workflows.
- IT departments managing JetBrains TeamCity installations.
What to do
It is imperative for affected organizations to assess their exposure to this vulnerability and take immediate action to mitigate risks. JetBrains has likely provided patches or workarounds that should be implemented as soon as possible.
- Review JetBrains' security advisory for CVE-2026-63077 for detailed guidance.
- Apply any available patches to TeamCity installations promptly.
- Restrict access to TeamCity servers to trusted networks only.
- Monitor for any unusual activity or unauthorized access attempts.