CVE-2025-53770
Critical 9.8 Exploited in the wild (KEV) Used in ransomware campaigns
Confirmed active exploitation — CISA KEV catalog
- Name
- Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
- Added to catalog
- Remediation due date (US federal)
- Required action
- 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.
Description
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.
Metrics
- CVSS 3.1
-
9.8 (CRITICAL)
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 100% (percentile: 100) as of 1 November 2026
- CWE
- CWE-502
Affected products
microsoft: sharepoint server
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770 Vendor Advisory
- https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulner… MitigationVendor Advisory
- https://arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-seve… ExploitPress/Media Coverage
- https://github.com/kaizensecurity/CVE-2025-53770 Exploit
- https://research.eye.security/sharepoint-under-siege/ ExploitMitigationThird Party Advisory
- https://news.ycombinator.com/item?id=44629710 Issue Tracking
- https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-g… Press/Media Coverage
- https://www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-e… Press/Media Coverage
- https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-… Mailing ListThird Party AdvisoryUS Government Resource
- https://www.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exp… Press/Media Coverage