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CVE-2026-63077

JetBrains TeamCity

score 90Known exploited · added 2026-08-05Used in ransomwarePublic PoC ×6Nuclei template

Summary

JetBrains TeamCity Deserialization of Untrusted Data Vulnerability

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

Published 2026-08-05 · first seen here 2026-10-10

CISA required action (due 2026-08-08): 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.

Analysis & write-ups

No technical write-up from a research team yet. Contact Zero checks Unit 42, Google/Mandiant, Microsoft, Talos, CrowdStrike, Rapid7, watchTowr and others several times a day, plus NVD and CISA reference links.

Exploit availability

Public exploit code lowers the bar for attackers, so prioritise patching and hunting. These repositories are unverified. Fake PoCs that contain malware are common, so never run them outside an isolated lab.

Where it shows in your logs

CISA requires forensic triage for this CVE (BOD 26-04): check affected systems for signs of compromise, don't just patch.

Server or web application · Unsafe deserialisation (remote code execution) medium confidence

What to look for

Data sources

Web server and WAF logs · ATT&CK DS0015 Application Log Content

Sentinel
W3CIISLogAppServiceHTTPLogsAzureDiagnostics (Application Gateway / Front Door WAF)_Im_WebSession
Splunk
Web.Webms:iis:autoaccess_combinedWAF / proxy sourcetypes
CrowdStrike
Falcon Next-Gen SIEM: third-party web / WAF / proxy logs

Process creation · ATT&CK DS0009 Process Creation

Sentinel
DeviceProcessEventsSecurityEvent (4688)Sysmon Event ID 1_Im_ProcessCreate
Splunk
Endpoint.ProcessesXmlWinEventLog:Microsoft-Windows-Sysmon/OperationalWinEventLog:Security (4688)
CrowdStrike
ProcessRollup2SyntheticProcessRollup2

File creation · ATT&CK DS0022 File Creation

Sentinel
DeviceFileEventsSysmon Event ID 11_Im_FileEvent
Splunk
Endpoint.FilesystemSysmon Event ID 11
CrowdStrike
NewExecutableWrittenNewScriptWritten*FileWritten events

Network connections · ATT&CK DS0029 Network Connection Creation / Network Traffic Flow

Sentinel
DeviceNetworkEventsCommonSecurityLog (firewall)_Im_NetworkSession
Splunk
Network_Traffic.All_TrafficFirewall sourcetypes (pan:traffic, fortigate_traffic, cisco:asa)
CrowdStrike
NetworkConnectIP4NetworkReceiveAcceptIP4NetworkConnectIP6

A generic baseline worked out from the product type and weakness (CWE-502), not a detection. Check table and field names against your environment. Hunt queries for Sigma, Splunk, Sentinel and CrowdStrike are coming.

News & advisories

References