Microsoft SharePoint Deserialization of Untrusted Data Vulnerability (CVE-2025-53770)
Severity: critical · Patch status: unpatched · Since 2025-07-20 · CVE-2025-53770
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. CISA added CVE-2025-53770 to its Known Exploited Vulnerabilities catalog on Jul 20, 2025, which means attackers are exploiting it in the wild. CISA reports known use in ransomware campaigns.
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.
- US federal agencies must remediate by Jul 21, 2025 (BOD 22-01); treat that as the outer limit.
Sources
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