CVE WatchAug 4, 2026

CVE-2025-53770

Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

CVSS

9.8

Critical

EPSS

100.0%

p100

KEV

YES

Jul 20, 2025

Exploit Today

0-100

Published: Jul 20, 2025 · Last modified: Aug 4, 2026 · CWE-502

EPSS · 30d

100.0%EPSS · 30 days100.0%

2026-08-022026-08-30

KEV catalog record

Product

Microsoft / SharePoint

Vulnerability

Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

Added to KEV

Jul 20, 2025

Remediate by

Jul 21, 2025

Known ransomware use

Yes

Summary description

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.

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.

Notes

CISA Mitigation Instructions: https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770; https://www.microsoft.com/en-us/security/blog/2025/07/22/disrupting-active-exploitation-of-on-premises-sharepoint-vulnerabilities/ ; https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770 ; https://nvd.nist.gov/vuln/detail/CVE-2025-53770

Technical 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.

Official references

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