Assessment
Why it matters
CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 100.0%; technical severity is CVSS 9.8.
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.
Who should care
- Teams operating SharePoint, Sharepoint Server
- Vulnerability and exposure management teams
- Security operations teams monitoring exploitation activity
Response plan
What I would do
- Confirm whether SharePoint, Sharepoint Server is present in the environment.
- Identify affected versions and establish whether vulnerable services are exposed or reachable.
- 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.
- Review relevant security telemetry for evidence of attempted or successful exploitation.
- Document the remediation decision and track it to verified completion.
Vendor remediation
Patch and remediation links
Use the vendor source below to confirm the correct fixed version, package or mitigation for your affected product.
Technical details
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CWE
- CWE-502
- Affected versions
- Microsoft SharePoint; Microsoft Sharepoint Server (Version: 2019)
- Published
- 19 July 2025
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
Signal timeline
- Added to CISA KEV
- Latest EPSS score: 100.0%
- Signal calculated at 88
External references
- Government advisory from www.cisa.gov
- Exploit information from arstechnica.com
- Exploit information from github.com
- Vendor advisory from msrc.microsoft.com
- Technical reference from news.ycombinator.com
- Mitigation guidance from research.eye.security
- Technical reference from therecord.media
- Technical reference from www.bleepingcomputer.com
- Government advisory from www.cisa.gov
- Technical reference from www.darkreading.com
- Technical reference from www.forbes.com
- Third-party advisory from x.com