Exploited vulnerability · CISA KEV

Is CVE-2026-63077 exploited? Yes: in CISA KEV since 5 Aug 2026

Gociux · JetBrains TeamCity · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2026-63077, JetBrains TeamCity Deserialization of Untrusted Data Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 5 Aug 2026, 9 days after it was published. It is known to be used in ransomware campaigns. It affects JetBrains TeamCity. If you run it, CISA's required action is: 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.

What it is

JetBrains TeamCity contains a deserialization of untrusted data vulnerability that could allow unauthenticated remote code execution via the agent polling protocol.

What to do

1. Check whether you run it. Look for TeamCity in your asset inventory, including appliances and cloud images. Stack check lists every exploited JetBrains CVE at once.
2. Apply the fix. 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.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 27 Jul 2026.
4. Get told next time. Email alerts when CISA adds a CVE for JetBrains.

Other exploited CVEs in TeamCity

• CVE-2024-27199: JetBrains TeamCity Relative Path Traversal Vulnerability (20 Apr 2026)
• CVE-2024-27198: JetBrains TeamCity Authentication Bypass Vulnerability (7 Mar 2024)
• CVE-2023-42793: JetBrains TeamCity Authentication Bypass Vulnerability (4 Oct 2023)

References

• blog.jetbrains.com/teamcity/2026/07/cve-2026-63077/
• www.jetbrains.com/privacy-security/issues-fixed/
• nvd.nist.gov/vuln/detail/CVE-2026-63077

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in August 2026 · JetBrains scorecard · act-now radar.