CVE-2023-42793 Vulnerability in TeamCity: Post-Mortem


  • A critical vulnerability issue for TeamCity On-Premises was discovered by the Sonar team. TeamCity Cloud was not affected.
  • The TeamCity team released the 2023.05.4 fix for the issue.
  • We created a plugin that works for older TeamCity versions (8.0+) and recommended installing it to all customers who could not upgrade quickly enough.
  • We notified all TeamCity On-Premises customers about the vulnerability.
  • The issue was publicly announced.

Actions taken by the TeamCity team

On September 6, 2023, we received a report from Sonar regarding a critical vulnerability issue identified in TeamCity On-Premises. If abused, the flaw could enable an unauthenticated attacker with HTTP(S) access to a TeamCity server to perform a remote code execution (RCE) attack and gain administrative control of the TeamCity server. 

We confirmed receiving the report on the same day and proceeded with the internal investigation. On September 14, 2023, we reported back to Sonar. We confirmed it to be a major security issue and stated that we had reproduced the issue and prepared a fix for it. Please refer to the Sonar blog post for technical details about how the issue can be reproduced.

We then proceeded with handling the issue. On September 18, 2023, we released version 2023.05.4 that contained a fix for the issue. We also created a plugin for older TeamCity versions (8.0+). Thanks to the plugin, any customers who were unable to update to the latest TeamCity version could still apply the fix.

The plugin can be downloaded here:

We then notified TeamCity Enterprise customers about the issue, encouraging them to update their servers to the latest version, 2023.05.4, which can be found here:

After that, the issue was publicly announced on September 21, 2023. Both the Sonar and TeamCity teams published blog posts about the discovered vulnerabilities.

We’d like to thank the Sonar team for discovering the issue and their collaboration on the public announcement.


September 6, 2023, 10:44 We received the report from the Sonar team.
September 6, 2023, 12:39We confirmed receipt of the report.
September 6, 2023, 12:54We reproduced the issue.
September 7, 2023We fixed the issue in the 2023.05.x branch.
September 12, 2023We prepared the plugin that could be used as a workaround.
September 14, 2023We sent an update to the Sonar team confirming a major security issue.
September 18, 2023TeamCity version 2023.05.4 with the vulnerability fixes was released.
September 18, 2023We sent notifications to customers asking them to update as soon as possible.
September 19, 2023CVE-2023-42793 was published.
September 21, 2023We published a blog post about the issue.
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