CVE-2025-53770
Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
IN CISA KEV
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.
- Vendor
- Microsoft
- Product
- SharePoint
- CVSS 3.1
- 9.8 (critical), scored by secure@microsoft.comCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CWE
- CWE-502
- Published
- 2025-07-20
- NVD modified
- 2026-08-04
- NVD status
- Analyzed
CISA KEV
- Date added
- 2025-07-20
- Due date
- 2025-07-21
- Ransomware use
- Known
- 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.
EPSS
100% chance of exploitation in the next 30 days (percentile 99th)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
References
- msrc.microsoft.com (Vendor Advisory)
- msrc.microsoft.com (Mitigation, Vendor Advisory)
- news.ycombinator.com (Issue Tracking)
- therecord.media (Press/Media Coverage)
- www.bleepingcomputer.com (Press/Media Coverage)
- www.cisa.gov (Mailing List, Third Party Advisory, US Government Resource)
- www.darkreading.com (Press/Media Coverage)
- www.forbes.com (Press/Media Coverage)
- x.com (Third Party Advisory)
- www.cisa.gov (US Government Resource)
Data last updated 18 Oct 2026. Sources: NVD API 2.0, CISA KEV catalog, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.