Microsoft SharePoint Deserialization of Untrusted Data
What to do
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.
CISA deadline 2025-07-21 · passed 1 year 1 month ago · applies to US federal civilian agencies; used elsewhere as a reference SLA
What happened
Microsoft SharePoint Server on-premises contains a deserialization of untrusted data vulnerability that could allow an unauthorized attacker to execute code over a network. This vulnerability could be chained with CVE-2025-53771. CVE-2025-53770 is a patch bypass for CVE-2025-49704, and the updates for CVE-2025-53770 include more robust protection than those for CVE-2025-49704.
Who is affected
Microsoft SharePoint. Affected version ranges are listed in the vendor advisory and the NVD entry linked under Sources.
Weakness class: CWE-502.
Timeline
- Added to CISA KEVExploitation in the wild confirmed by CISA
- CISA remediation deadlinepassed 1 year 1 month ago
Sources
- NVD entry for CVE-2025-53770 nvd.nist.gov/vuln/detail/CVE-2025-53770
- CISA Known Exploited Vulnerabilities catalog www.cisa.gov/known-exploited-vulnerabilities-catalog
- cisa.gov www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770
- microsoft.com www.microsoft.com/en-us/security/blog/2025/07/22/disrupting-active-exploitation-of-on-premises-sharepoint-vulnerabilities/
- msrc.microsoft.com msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770
- nvd.nist.gov nvd.nist.gov/vuln/detail/CVE-2025-53770