Successful exploitation of CVE-2025-53770 could expose MachineKey configuration details from a vulnerable SharePoint Server, ultimately enabling unauthenticated remote code execution.

CVE-2025-53770: Frequently Asked Questions About Zero-Day SharePoint Vulnerability Exploitation

Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized attacker to execute code over a network. Microsoft is aware that an exploit for CVE-2025-53770 exists in the wild. Microsoft is preparing and fully testing a comprehensive update to address this vulnerability. In the meantime, please make sure that the mitigation provided in this CVE documentation is in place so that you are protected from exploitation.

Continued exploitation has been observed for a series of SharePoint vulnerabilities dubbed "ToolShell" including recent reports of further ransomware deployment.

Patches are available for CVE-2025-53770 across SharePoint Server 2016, 2019 and Subscription Edition, as active exploitation continues.

Zero-day in Microsoft SharePoint Server is under active exploitation according to multiple firms. No patch available yet. Mitigation instructions available.

Patches are available for SharePoint Server 2016, 2019 and Subscription Edition, as active exploitation continues.

The version of Sitecore XP running on the remote host is affected by an insecure deserialization vulnerability.
Sitecore deployments using the sample key provided with deployment instructions for XP 9.0 or earlier and Active Directory 1.4 are potentially vulnerable to an insecure ViewState deserialization vulnerability that could allow a remote, unauthenticated attacker to perform remote code execution and acquire non-authorized access to information.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Microsoft SharePoint Server Subscription Edition < 16.0.18526.20508 or 2016 < 16.0.5513.1001 or 2019 < 16.0.10417.20037 is affected by a vulnerability that allows an unauthenticated attacker to execute arbitrary code through insecure deserialization.

The Microsoft SharePoint Server 2016 installation on the remote host is missing security updates. It is, therefore, affected by multiple security vulnerabilities:

  - Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized     attacker to execute code over a network. (CVE-2025-53770)

  - Improper limitation of a pathname to a restricted directory ('path traversal') in Microsoft     Office SharePoint allows an authorized attacker to perform spoofing over a network. (CVE-2025-53771)

The Microsoft SharePoint Server Subscription Edition installation on the remote host is missing security updates. It is, therefore, affected by multiple security vulnerabilities:

  - Improper limitation of a pathname to a restricted directory ('path traversal') in Microsoft     Office SharePoint allows an authorized attacker to perform spoofing over a network. (CVE-2025-53771)

  - Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized     attacker to execute code over a network. (CVE-2025-53770)

The Microsoft SharePoint Server 2019 installation on the remote host is missing security updates. It is, therefore, affected by multiple vulnerabilities:

  - Improper limitation of a pathname to a restricted directory ('path traversal') in Microsoft     Office SharePoint allows an authorized attacker to perform spoofing over a network. (CVE-2025-53771)

  - Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized     attacker to execute code over a network. (CVE-2025-53770)

ID	Name	Product	Family	Severity
261484	Sitecore XP Insecure Deserialization (SC2025-005)	Nessus	CGI abuses	critical
114923	Microsoft SharePoint Remote Code Execution	Web App Scanning	Component Vulnerability	critical
242480	Security Updates for Microsoft SharePoint Server 2016 (July 2025)	Nessus	Windows : Microsoft Bulletins	high
242415	Security Updates for Microsoft SharePoint Server Subscription Edition (July 2025)	Nessus	Windows : Microsoft Bulletins	critical
242414	Security Updates for Microsoft SharePoint Server 2019	Nessus	Windows : Microsoft Bulletins	critical

Detections

Analytics

CVE-2025-53770

critical

Tenable Plugins

critical

critical

high

critical

critical