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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2025-53770
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770
• 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
• https://github.com/kaizensecurity/CVE-2025-53770
• https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globally