Assessment
Why it matters
CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 98.2%; technical severity is CVSS 7.3.
Microsoft Exchange Server Information Disclosure Vulnerability
Who should care
- Teams operating Exchange Server
- Vulnerability and exposure management teams
- Security operations teams monitoring exploitation activity
Response plan
What I would do
- Confirm whether Exchange Server is present in the environment.
- Identify affected versions and establish whether vulnerable services are exposed or reachable.
- Microsoft Security patch CVE-2021-33766
- Review relevant security telemetry for evidence of attempted or successful exploitation.
- Document the remediation decision and track it to verified completion.
Treatment intelligence
Remediation intelligence
Vendor sources are listed before government and third-party guidance. Confirm product applicability and change prerequisites before deployment.
Verification noteAutomated link verification has not completed for this guidance yet.
Patch
Technical details
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- CWE
- CWE-287
- Affected versions
- Microsoft Exchange Server (Version 2013 | Version 2016 | Version 2016 | Version 2019)
- Fixed versions
- No explicit fixed version is currently recorded.
- Published
- 14 July 2021
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
Signal timeline
- CVE published
- Added to CISA KEV
- Latest EPSS score: 98.2%
- Signal calculated at 82