Known Exploited cybersecurity update: CISA Flags TeamCity CVE-2026-63077 RCE Flaw Under Active Exploitation in the Wild. The report references CVE-2026-63077. At least one associated vulnerability is present in the CISA Known Exploited Vulnerabilities catalog, increasing the urgency for affected organizations to review exposure and vendor remediation guidance. NetworkFix reviewed the available source material to summarize the security issue, its potential impact and the defensive actions administrators should prioritize.
What Happened
A newly patched security flaw impacting on-premise versions of JetBrains TeamCity has come under active exploitation in the wild, according to the U.S. Cybersecurity and Infrastructure Security Agency (CISA). The vulnerability in question is CVE-2026-63077 (CVSS score: 9.8), a case of deserialization of untrusted data that could allow an unauthenticated attacker with access to a TeamCity server CISA Flags TeamCity CVE-2026-63077 RCE Flaw Under Active Exploitation in the Wild Reach out to get featured—contact us to send your exclusive story idea, research, hacks, or ask us a question or leave a comment/feedback! Ravie Lakshmanan Aug 06, 2026 Vulnerability / Enterprise Security A newly patched security flaw impacting on-premise versions of JetBrains TeamCity has come under active exploitation in the wild , according to the U.S. The vulnerability in question is CVE-2026-63077 (CVSS score: 9.8), a case of deserialization of untrusted data that could allow an unauthenticated attacker with access to a TeamCity server to bypass authentication checks and execute arbitrary operating system commands with the privileges of the TeamCity server process. "JetBrains TeamCity contains a deserialization of untrusted data vulnerability that could allow unauthenticated remote code execution via the agent polling protocol," CISA said . According to JetBrains, the vulnerability can be exploited by an unauthenticated attacker via the TeamCity agent polling protocol to sidestep authentication checks and execute arbitrary operating system commands. The exact impact varies depending on the privileges granted to the TeamCity server process.
Technical Details
The vulnerability identifiers associated with this report are CVE-2026-63077. The highest CVSS score detected in the available material is 9.8. A successful attack can expose TeamCity data, configurations, and stored credentials, modify server state, and potentially compromise the integrity of build artifacts and downstream CI/CD pipelines, per JetBrains. It's currently not known how the vulnerability is being exploited in the wild, the identity of the threat actors behind the attacks, and the scale of such efforts. JetBrains has yet to update its advisory to confirm active exploitation. In light of the latest development, users running on-premise versions are recommended to apply the updates as soon as possible. Per Binding Operational Directive (BOD) 26-04, Federal Civilian Executive Branch (FCEB) agencies are required to prioritize patching high-risk vulnerabilities listed in the Known Exploited Vulnerabilities (KEV) catalog. The deadline by which federal agencies must apply software patches or mitigations for CVE-2026-63077 is August 8, 2026. Follow us on Google News , Twitter and LinkedIn to read more exclusive content we post. Share on Facebook Share on Twitter Share on Linkedin Share on Reddit Share on Hacker News Share on Email Share on WhatsApp Share on Facebook Messenger Share on Telegram Application Security , CI/CD Security , Cyber Attack , DevOps , enterprise security , remote code execution , Software Security , Supply Chain Security , Vulnerability New Bit2Watt Attack Could Let Cloud Tenants Disrupt Power Grids Without an Exploit Open-Source Android AI Agents Could Let Invisible Screen Text Run Code on Host PCs Critical SharePoint RCE CVE-2026-50522 Under Active Exploitation After Public PoC AWS Kiro Flaw Let a Poisoned Web Page Rewrite Its Config and Run Code Apple Fixes Hide My Email Bug That Exposed Real Addresses in Mail Logs Microsoft Azure DevOps MCP Flaw Lets Hidden PR Comments Hijack AI Review Agents OpenAI Says Its AI Models Escaped Sandbox, Targeted Hugging Face to Cheat Benchmark Adobe Acrobat Extension Flaw Let Malicious Sites Read WhatsApp Web Data Ubuntu snap-confine Flaw Could Give Local Users Root on Default Desktop Installs Nine-Year-Old RefluXFS Linux Flaw Gives Local Users Root on Default RHEL Installs Attackers Weaponize GitHub Actions Runners to Target cPanel and WHM Servers Claude Cowork Flaw Could Let AI Agent Escape Its VM and Access Mac Files ThreatsDay: Android Spyware, PLC Attacks, AI Image Prompt Injection + 12 More Stories Kimi K3 Agents Found Redis Zero-Days and Built RCE Exploit, Researchers Say Hacker Runs Hermes AI Agent Unattended for Post-Exploitation at Thai Finance Ministry ChatGPT AgentForger Flaw Could Deploy Rogue Workspace Agents via a Phishing Link Certighost Exploit Lets Low-Privileged Active Directory Users Impersonate a Domain Controller Researcher Publishes GitLab RCE PoC Letting Authenticated Users Run Commands as Git Fastjson 1.x RCE Vulnerability Targeted in Attacks With No Patched Available Malvertising Sends Malware in Pieces, Then Makes the Browser Build the Executable [Webinar] How Militaries Can Trust the Data Behind Autonomous Missions Download the 5-Step Action Plan for AI-Speed Exploitation Get the Checklist for Gaining Control of AI Use Across Your Organization Get the 2026 CISO Benchmark Report Based on 600 Security Leaders How to Secure AI Code Before It Reaches Production Learn how 300 enterprise leaders are managing AI-driven open-source risk, remediation debt, and governance at scale. How to Secure AI-Built Software at Machine Speed Learn how to govern risk, secure AI-built software, and keep control as development moves at machine speed.
Security Impact
Organizations using the affected technology should treat the report according to its known exploited severity classification. CISA KEV inclusion indicates evidence of exploitation and is a strong signal that remediation should be prioritized rather than handled as a routine maintenance item. 11 Real Stories: How Identity Exposure Unlocks Active Attack Paths Map cross-domain privilege escalation to sever breach routes at key choke points. Burp, sqlmap, SSRF, XXE, SSTI: Web Exploitation, Hands-On 35 labs plus a live CTF take you from recon to remote code execution. Learn how practitioners are applying AI to today's cybersecurity challenges. How AI-Assisted Attacks Are Breaking Legacy SIEM Tools Claude Runs Across Six Surfaces in Your Company.
Recommended Actions
- Identify whether the affected product, service or software is present in the environment.
- Review the original vendor or research advisory and verify affected versions before making configuration changes.
- Prioritize remediation because the associated CVE appears in the CISA Known Exploited Vulnerabilities catalog.
- Apply vendor-provided security updates or mitigations as soon as operationally practical.
- Review relevant security logs and monitoring alerts for signs of suspicious activity associated with the reported issue.
- Use the CVE identifiers, where available, to validate exposure through vulnerability-management and asset-inventory tools.
Security Details
- Severity: Known Exploited
- CVE: CVE-2026-63077
- CVSS Score: 9.8
- CISA KEV: Yes — CVE-2026-63077
- Original source: The Hacker News
Why This Matters
Cybersecurity teams should use reports like this as an input to risk-based vulnerability and threat management rather than relying on headline severity alone. Exposure depends on whether the affected technology is deployed, reachable by an attacker and protected by compensating controls. Confirming asset ownership, affected versions and available vendor fixes helps teams prioritize remediation while avoiding unnecessary emergency changes.
Original Report
NetworkFix recommends reviewing the complete original report from The Hacker News for the authoritative technical context, affected versions, indicators and vendor-specific remediation details: Read the original report.
