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What is the Attack? |
An active campaign has been linked, with medium confidence, to a threat actor designated UAT-8837, which Cisco Talos assesses as a China-nexus group targeting critical infrastructure organizations in North America. Observed activity includes targeted intrusions aimed at gaining initial access, credential harvesting, and internal reconnaissance. UAT-8837 primarily gains initial access by exploiting public-facing application vulnerabilities, including both known n-day flaws and previously undisclosed zero-day vulnerabilities. In recent activity, the actor exploited CVE-2025-53690, a ViewState deserialization zero-day vulnerability in Sitecore products, indicating access to advanced exploitation capabilities and potential use of zero-day exploits. Sitecore is a widely used digital experience platform (DXP) that provides content management, personalization and e-commerce capabilities for enterprises. The flaw enables preauthentication remote code execution (RCE) against internet-facing Sitecore deployments. |
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What is the recommended Mitigation? |
• Organizations should immediately patch and remediate all exposed public-facing applications, with priority given to Sitecore deployments affected by CVE-2025-53690. Security Bulletin SC2025-005 |
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What FortiGuard Coverage is available? |
• FortiGuard Labs is actively monitoring this threat activity and will continue to provide updates as the situation evolves, including new intelligence, indicators, and protection guidance. |






