CVE-2020-0688
Published: November 3, 2021
Official Description
Microsoft Exchange Server Validation Key fails to properly create unique keys at install time, allowing for remote code execution.
CISA KEV Advisory
Microsoft Exchange Server Validation Key Remote Code Execution Vulnerability
Microsoft Exchange Server Validation Key fails to properly create unique keys at install time, allowing for remote code execution.
Apply updates per vendor instructions.
Risk Analysis
This vulnerability in Microsoft Exchange Server's validation key mechanism allows for remote code execution due to improper key generation during installation. The very high EPSS score indicates a strong likelihood of exploitation, and its inclusion in CISA's KEV confirms active exploitation, making this a critical and urgent issue.
Active exploitation of this vulnerability has been observed in the wild, indicating that working exploits are readily available and being used by attackers. This flaw is remotely exploitable.
Apply the latest security updates from Microsoft for Exchange Server. Ensure that Exchange servers are properly configured and exposed only to trusted networks.
Technical Analysis
CVE-2020-0688 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2020-0688 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Affected Vendors & Products
Exploit & PoC Resources
All References (1)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2020-0688 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1