CVE-2026-63077: in the CISA KEV catalogue
JetBrains TeamCity Deserialization of Untrusted Data Vulnerability. CISA added CVE-2026-63077 to the Known Exploited Vulnerabilities catalogue on 2026-08-05 with a default due date of 2026-08-08. Known ransomware campaign use: Known. Forensic triage flag: Yes.
JetBrains TeamCity contains a deserialization of untrusted data vulnerability that could allow unauthenticated remote code execution via the agent polling protocol. (CISA description)
- Vendor / product
- JetBrains TeamCity
- CWE
- CWE-502
- CISA required action
- 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.
- EPSS
- 94%, percentile 99 (scored 2026-11-03)
EPSS puts about 94 in 100 odds (94%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
- https://blog.jetbrains.com/teamcity/2026/07/cve-2026-63077/
- https://www.jetbrains.com/privacy-security/issues-fixed/
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-63077
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2026-63077 in the CISA KEV catalogue?
Yes. CISA added CVE-2026-63077 (JetBrains TeamCity Deserialization of Untrusted Data Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2026-08-05. CISA's default due date for it is 2026-08-08.
Is CVE-2026-63077 used in ransomware attacks?
CISA marks known ransomware campaign use as Known for CVE-2026-63077.
What should I do about CVE-2026-63077?
CISA's required action: 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.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2026-63077