Risk Letters

Exploited vulnerability

CVE-2025-53770

TLP:CLEAR

Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

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.

Facts

  • Vendor: Microsoft
  • Product: SharePoint
  • CVSS: 9.8
  • EPSS (probability of exploitation within 30 days): 100 %
  • On CISA's Known Exploited Vulnerabilities list since: 20 July 2025
  • First known exploitation: 20 July 2025
  • Used in ransomware campaigns (per CISA): Yes
  • CISA's deadline for US federal agencies: 21 July 2025
  • Weakness: CWE-502
  • First seen by Risk Letters: 20 July 2025

Members see which Nordic sectors the flaw hits, and what to do about it.

Get the full brief

Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD