Hackers Hit Zero-Day Flaw in Microsoft's SharePoint
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The name was coined by Dinh Ho Anh, a researcher from Khoa of Viettel Cyber Security, who developed the exploit. The researcher said he picked the name because it exploited ToolPane.aspx, a component for assembling the side panel view in the SharePoint user interface.
More information has emerged on the ToolShell SharePoint zero-day attacks, including impact, victims, and threat actors.
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) issued an alert Sunday detailing active exploitation of a critical SharePoint vulnerability, CVE-2025-53770.
Microsoft also has issued a patch for a related SharePoint vulnerability — CVE-2025-53771; Microsoft says there are no signs of active attacks on CVE-2025-53771, and that the patch is to provide more robust protections than the update for CVE-2025-49706.
More details emerged on the ToolShell zero-day attacks targeting SharePoint servers, but confusion remains over the vulnerabilities.