CISA recommends configuring AMSI integration in SharePoint and deploying Defender AV on all SharePoint servers. If AMSI cannot be enabled, CISA recommends disconnecting affected products that are public-facing on the internet from service until official mitigations are available. Once mitigations are provided, apply them according to CISA and vendor instructions. Follow the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.  

Disconnect public-facing versions of SharePoint Server that have reached their end-of-life (EOL) or end-of-service (EOS) to include SharePoint Server 2013 and earlier versions. For supported versions, please follow the mitigations according to CISA (URL listed below in Notes) and vendor instructions (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.

CVE: https://arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-severity-rating-is-under-exploit-across-the-globe/ Types: Exploit, Press/Media Coverage

CVE: https://news.ycombinator.com/item?id=44629710 Types: Issue Tracking

CVE: https://www.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exploited-sharepoint-toolshell-flaw Types: Press/Media Coverage

https://arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-severity-rating-is-under-exploit-across-the-globe/

https://www.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exploited-sharepoint-toolshell-flaw

https://news.ycombinator.com/item?id=44629710

OR
          *cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*
          *cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
          *cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:* versions up to (excluding) 16.0.18526.20508

CVE: https://github.com/kaizensecurity/CVE-2025-53770 Types: Exploit

CVE: https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770/ Types: Mitigation, Vendor Advisory

CVE: https://research.eye.security/sharepoint-under-siege/ Types: Exploit, Mitigation, Third Party Advisory

CVE: https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globally Types: Press/Media Coverage

CVE: https://www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-exploited-in-rce-attacks-no-patch-available/ Types: Press/Media Coverage

CVE: https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770 Types: Mailing List, Third Party Advisory, US Government Resource

CVE: https://www.forbes.com/sites/daveywinder/2025/07/20/microsoft-confirms-ongoing-mass-sharepoint-attack---no-patch-available/ Types: Press/Media Coverage

CVE: https://x.com/Shadowserver/status/1946900837306868163 Types: Third Party Advisory

Microsoft Corporation: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770 Types: Vendor Advisory

https://github.com/kaizensecurity/CVE-2025-53770

https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globally

2025-07-20

2025-07-21

CISA recommends configuring AMSI integration in SharePoint and deploying Defender AV on all SharePoint servers. If AMSI cannot be enabled, CISA recommends disconnecting affected products that are public-facing on the internet from service until official mitigations are available. Once mitigations are provided, apply them according to CISA and vendor instructions. Follow the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.  

Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770/

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

https://www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-exploited-in-rce-attacks-no-patch-available/

https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770

https://www.forbes.com/sites/daveywinder/2025/07/20/microsoft-confirms-ongoing-mass-sharepoint-attack---no-patch-available/

https://x.com/Shadowserver/status/1946900837306868163

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.

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE-502

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770