{"id":"CVE-2021-34523","aliases":[],"url":"https://o3.security/vulnerability/CVE-2021-34523","summary":"Microsoft Exchange Server Elevation of Privilege Vulnerability","details":"Microsoft Exchange Server Elevation of Privilege Vulnerability","published":"2021-07-14T18:15:12.347","modified":"2026-08-10T19:59:11.883","cvss":{"score":9,"severity":"CRITICAL","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N"},"epss":{"score":0.9999,"percentile":0.99985,"asOf":"2026-08-27"},"cisaKev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","knownRansomwareCampaignUse":true},"exploitsKnown":6,"affectedPackages":[],"fix":null,"references":[{"type":"FIX","url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34523"},{"type":"EXPLOIT","url":"http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html"},{"type":"FIX","url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34523"},{"type":"ADVISORY","url":"https://www.zerodayinitiative.com/advisories/ZDI-21-822/"},{"type":"WEB","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34523"}],"provenance":{"sources":["OSV.dev","NVD","CISA KEV","FIRST.org (EPSS)"],"lastVerified":"2026-08-10T19:59:11.883"}}