CVE-2021-31207VulnerabilityPublished 11/03/2021Updated 10/24/2026
CVE-2021-31207: Microsoft Exchange Server Security Feature Bypass Vulnerability
Affects Microsoft Exchange ServerSource CISA KEV
Severity
HighNo CVSS score published yet
- Exploitation
Actively exploited – in CISA KEV since 11/03/2021
- KEV deadline
- 11/17/2021
- Ransomware
- Used in ransomware campaigns
- EPSS
- 99.8% chance of exploitation in 30 days – higher than 99% of CVEs
What to do
CISA required action
Apply updates per vendor instructions.
Description
CVE-2021-31207 is a security feature bypass vulnerability in Microsoft Exchange Server. It allows attackers to circumvent security mechanisms, potentially leading to unauthorized actions. This vulnerability has been exploited in the wild and is associated with known ransomware campaigns. No specific affected versions or patch information is provided in the available data.