Assessment
Why it matters
CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 90.4%; technical severity is CVSS 8.8.
Microsoft Exchange Server Remote Code Execution Vulnerability
Who should care
- Teams operating Exchange, Exchange Server
- Vulnerability and exposure management teams
- Security operations teams monitoring exploitation activity
Response plan
What I would do
- Confirm whether Exchange, Exchange Server is present in the environment.
- Identify affected versions and establish whether vulnerable services are exposed or reachable.
- Apply updates per vendor instructions.
- Review relevant security telemetry for evidence of attempted or successful exploitation.
- Document the remediation decision and track it to verified completion.
Vendor remediation
Patch and remediation links
Use the vendor source below to confirm the correct fixed version, package or mitigation for your affected product.
Technical details
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CWE
- CWE-184
- Affected versions
- Microsoft Exchange; Microsoft Exchange Server (Version: 2019)
- Published
- 10 November 2021
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
Signal timeline
- CVE published
- Added to CISA KEV
- Latest EPSS score: 90.4%
- Signal calculated at 86