Risk Letters

Exploited vulnerability

CVE-2021-31207

TLP:CLEAR

Microsoft Exchange Server Security Feature Bypass Vulnerability

Microsoft Exchange Server contains an unspecified vulnerability that allows for security feature bypass.

Facts

  • Vendor: Microsoft
  • Product: Exchange Server
  • CVSS: 6.6
  • EPSS (probability of exploitation within 30 days): 99.8 %
  • On CISA's Known Exploited Vulnerabilities list since: 3 November 2021
  • First known exploitation: 3 November 2021
  • Used in ransomware campaigns (per CISA): Yes
  • CISA's deadline for US federal agencies: 17 November 2021
  • Weakness: CWE-20
  • First seen by Risk Letters: 3 November 2021

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