Eye Security Uncovers Actively Exploited Zero-Day in Microsoft SharePoint (CVE-2025-53770)

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Written by Eye Security

On the evening of July 18, 2025, Eye Security identified active, large-scale exploitation of a new SharePoint remote code execution (RCE) vulnerability chain, dubbed ToolShell. This exploit is being used in the wild to compromise on-premise SharePoint servers across the world. The new chain we elaborate in this blog, was later named CVE-2025-53770 by Microsoft, as it is a variant of CVE-2025-49706.

Please find more details on our Tech Blog that’s actively being maintained by our Research Team:

https://research.eye.security/sharepoint-under-siege/

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Threats and Vulnerabilities

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Eye Security

Eye Security is a leading European cybersecurity company specialising in advanced cyber protection, Managed Detection and Response (MDR), and 24/7 Security Operations Centre (SOC) services. Founded by former Dutch national security experts, Eye Security helps businesses across Europe protect against ransomware, phishing attacks, data breaches and evolving cyber threats. Through its AI-powered cybersecurity platform, Eye Cyber Guard, the company delivers comprehensive cyber threat detection, incident response, vulnerability management, security awareness training and integrated cyber insurance . Supporting organisations across industries including logistics, manufacturing, healthcare and professional services, Eye Security helps businesses strengthen their cyber resilience, improve information security and navigate European cybersecurity regulations, including NIS2, GDPR and DORA. With a focus on proactive threat prevention, cyber risk management and business continuity, Eye Security provides expert cybersecurity insights, practical guidance and industry best practices to help organisations stay secure in an increasingly complex digital landscape.

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