CVE Exploit Alert: CVE-2024-27199 | HIGH | CVSS 7.3 | JetBrains TeamCity

HIGH

Alert Date: 2026-05-02

Severity Overview

Summary

In JetBrains TeamCity before 2023.11.4 path traversal allowing to perform limited admin actions was possible

What the Attack Looks Like

If successfully exploited: CISA has confirmed known ransomware campaign use for this CVE. This is not a theoretical risk — organizations with unpatched systems should treat this as an active incident response scenario, not just a patch management item.

Analyst Takeaway

The attack is launched over the network (remotely exploitable without physical access) and no authentication is required. This vulnerability is already in CISA KEV, which means exploitation has been confirmed in the wild — treat this as active risk, not theoretical exposure. CISA indicates known ransomware campaign use, which raises the likelihood of rapid operational impact if vulnerable systems remain exposed. In parallel with patching, defenders should review external exposure, hunt for signs of exploitation, and validate whether compensating controls are in place for vulnerable assets.

Detection Guidance

Recommended Actions

Immediate (0–24 Hours)

• Inventory: Identify all systems running JetBrains TeamCity. Include production, staging, dev, and cloud environments — untracked instances are the most likely to remain unpatched.
• Validate internet-facing exposure: Determine which of the affected systems are reachable from the public internet. Prioritize these for immediate remediation or compensating controls.
• Apply compensating controls now: For systems that cannot be patched immediately, implement temporary mitigations: restrict access via firewall rules or ACLs, add WAF rules if applicable, disable or isolate the vulnerable component if feasible without breaking critical operations.
• Escalate and prepare for incident response: CISA has confirmed ransomware campaign use. Notify your security leadership, ensure backup integrity is validated and tested, and confirm your IR playbook is ready to activate if exploitation is detected.

Remediation

• Apply the vendor patch: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
• CISA directive deadline: 2026-05-04 — this is the mandatory deadline for US federal civilian agencies under BOD 22-01. All organizations should treat this date as a strong target regardless of federal mandate.
• Verify remediation: After patching, confirm the correct version is installed on all affected hosts. Run a vulnerability scan or use your asset management tooling to verify — do not rely solely on change tickets.

Detection Coverage

• Unauthenticated exploitation monitoring: Because this vulnerability requires no authentication, internet-facing scanning and exploitation attempts may begin within hours of public disclosure. Ensure alerting is in place before the end of the day.
• Threat intelligence feeds: Monitor your TI feeds and vendor advisory channels for published indicators of compromise (IOCs), proof-of-concept exploit releases, or active campaign reporting associated with this CVE — these should trigger an immediate hunt even if no internal alerts have fired.

Vulnerability Details

Additional Notes

https://www.jetbrains.com/privacy-security/issues-fixed/ ; 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/ ; https://nvd.nist.gov/vuln/detail/CVE-2024-27199