CVE-2025-53770

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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
9.8 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
microsoftCNA
9.8 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:W/RC:C
CISA-ADPADP
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CVEADP
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Base Score
CVSS 3.x
EPSS Score
Percentile: 99%
VendorProductVersion
microsoftsharepoint_server
𝑥
< 16.0.18526.20508
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770
https://arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-severity-rating-is-under-exploit-across-the-globe/
https://github.com/kaizensecurity/CVE-2025-53770
https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770/
https://news.ycombinator.com/item?id=44629710
https://research.eye.security/sharepoint-under-siege/
https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globally
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.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exploited-sharepoint-toolshell-flaw
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://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53770