CVSS 3.1
9.0 criticalCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:NCVE-2021-34523
Critical (9.0) in Microsoft Exchange Server. In CISA KEV since 2021-11-03, with known ransomware use. EPSS 100% chance of exploitation in the next 30 days.
Microsoft Exchange Server Elevation of Privilege Vulnerability
Severity
- EPSS
- 100% chance of exploitation in the next 30 days; higher than 99% of CVEs (scores of 2026-10-31)
- CISA KEV
- listed 2021-11-03, due 2021-11-17, known ransomware use
- Published
- Modified
- Record from
- the NVD, synced
Affected
- microsoft:exchange_server
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34523
- http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34523
- https://www.zerodayinitiative.com/advisories/ZDI-21-822/
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34523