{"id":"CVE-2021-34473","title":"Microsoft Exchange Server Remote Code Execution Vulnerability","summary":"Microsoft Exchange Server Remote Code Execution Vulnerability","severity":"critical","cvss":9.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","cwe":["CWE-918","CWE-918"],"vendor":"microsoft","product":"exchange_server","affected":["exchange_server = 2013","exchange_server = 2016","exchange_server = 2019"],"published":"2021-07-14","updated":"2026-08-10","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-34473","references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34473","label":"secure@microsoft.com"},{"url":"http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34473","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-21-821/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34473","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd","kev","in-the-wild","exploit-available"],"epss":0.99999,"epssPercentile":0.99997,"kev":true,"kevDateAdded":"2021-11-03","kevDueDate":"2021-11-17","kevRansomware":true,"exploited":true,"zeroDay":true,"ingestedAt":"2026-08-10T16:41:16.185Z","exploits":{"github":9,"githubRepos":["https://github.com/cyberheartmi9/Proxyshell-Scanner","https://github.com/RaouzRouik/CVE-2021-34473-scanner","https://github.com/p2-98/CVE-2021-34473"],"metasploit":["exploit/windows/http/exchange_proxyshell_rce"],"nuclei":["CVE-2021-34473"],"checkedAt":"2026-09-08T15:36:49.424Z"},"exploitAvailable":true,"slug":"CVE-2021-34473","body":"## Overview\n\nMicrosoft Exchange Server Remote Code Execution Vulnerability\n\n## Affected\n\n- `exchange_server = 2013`\n- `exchange_server = 2016`\n- `exchange_server = 2019`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"hadal","depthScore":100,"depthScoreParts":{"impact":50.1,"likelihood":20,"exploitation":25,"ransomware":5},"changes":[{"seq":4524,"id":"CVE-2021-34473","ts":1788887187674,"field":"exploit_available","old":"false","new":"true"},{"seq":3407,"id":"CVE-2021-34473","ts":1788886305348,"field":"exploit_available","old":"true","new":"false"},{"seq":2262,"id":"CVE-2021-34473","ts":1788882974844,"field":"exploit_available","old":"false","new":"true"},{"seq":1291,"id":"CVE-2021-34473","ts":1788882386642,"field":"exploit_available","old":"true","new":"false"},{"seq":405,"id":"CVE-2021-34473","ts":1788881822400,"field":"exploit_available","old":"false","new":"true"}]}