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JetBrains TeamCity Authentication Bypass Vulnerabilities Actively Exploited

March 5, 2024 | 2 MINS READ

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On March 4th, JetBrains released TeamCity 2023.11.4 to address two authentication bypass vulnerabilities in the web component of TeamCity. The vulnerabilities, tracked as CVE-2024-27198 (CVSS: 9.8) and CVE-2024-27199 (CVSS 7.3), allow unauthenticated attackers with HTTP(S) access to bypass authentication checks and potentially gain administrative control.

As of March 5th, GreyNoise observed active exploitation of CVE-2024-27198.

It is critical that organizations apply the relevant security patches, or mitigations, to address these vulnerabilities immediately as exploitation is ongoing.

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JetBrains TeamCity is a Continuous Integration and Continuous Delivery (CI/CD) solution that helps developers automate the building and testing of products. Successful exploitation could not only compromise the CI/CD environment but also enable attackers to tamper with software builds and conduct further attacks downstream in the supply chain.

In their release, JetBrains confirmed “TeamCity Cloud servers have already been patched, and we have verified that they weren’t attacked.”

The observation of in-the-wild exploitation CVE-2024-27198 only a day after release highlights the importance of timely system patching. When vulnerabilities are actively being exploited by threat actors, the stakes for unpatched systems escalate dramatically, transforming theoretical risks into immediate threats.

Prior to in-the-wild exploitation, Proof of Concept (PoC) exploit code for CVE-2024-27198 was released. The publication of PoC exploit code significantly escalates the risk associated with known vulnerabilities accelerating the transition from targeted to widespread exploitation. The release of exploit code effectively lowers the barrier to entry for cybercriminals, providing even those with limited technical skills access to powerful tools for exploiting vulnerabilities.

It should be noted that systems will be vulnerable to both CVEs as they were fixed in the same update. Since the potential impact of CVE-2024-27198 is higher than CVE-2024-27199, CVE-2024-27198 has been the focus of exploit developers and threat actors.


[1] https://blog.jetbrains.com/teamcity/2024/03/teamcity-2023-11-4-is-out/
[2] https://blog.jetbrains.com/teamcity/2024/03/additional-critical-security-issues-affecting-teamcity-on-premises-cve-2024-27198-and-cve-2024-27199-update-to-2023-11-4-now/
[3] https://www.rapid7.com/blog/post/2024/03/04/etr-cve-2024-27198-and-cve-2024-27199-jetbrains-teamcity-multiple-authentication-bypass-vulnerabilities-fixed/
[4] https://viz.greynoise.io/tags/teamcity-jetbrain-cve-2024-27198-auth-bypass-attempt

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