{"id":"CVE-2021-42321","aliases":["EUVD-2021-29296","GHSA-3f87-66x4-f3p7"],"status":"published","title":"Microsoft Exchange Server Remote Code Execution Vulnerability","description":"Microsoft Exchange Server Remote Code Execution Vulnerability","severity":{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.91737,"percentile":0.99818,"model":"v2026.06.15"},"facts":{"in_kev":true,"known_exploited":true,"public_exploit":true,"fix_available":false},"cwes":["CWE-184","CWE-502"],"published":"2021-11-10T00:47:43Z","modified":"2026-08-19T19:23:07Z","kev":{"date_added":"2021-11-17","due_date":"2021-12-01","required_action":"Apply updates per vendor instructions.","known_ransomware_use":"Known"},"exploitation":[{"source":"euvd","since":"2021-11-17"},{"source":"kev","since":"2021-11-17"}],"exploits":[{"source":"pocgithub","id":"DarkSprings/CVE-2021-42321","title":"DarkSprings/CVE-2021-42321","date":"2021-11-23","url":"https://github.com/DarkSprings/CVE-2021-42321"},{"source":"metasploit","id":"exploit/windows/http/exchange_chainedserializationbinder_rce","title":"Microsoft Exchange Server ChainedSerializationBinder RCE","type":"exploit","platform":"Windows","date":"2021-12-09","verified":true,"url":"https://www.rapid7.com/db/modules/exploit/windows/http/exchange_chainedserializationbinder_rce"},{"source":"pocgithub","id":"timb-machine-mirrors/testanull-CVE-2021-42321_poc.py","title":"timb-machine-mirrors/testanull-CVE-2021-42321_poc.py","date":"2022-01-05","url":"https://github.com/timb-machine-mirrors/testanull-CVE-2021-42321_poc.py"},{"source":"pocgithub","id":"7BitsTeam/exch_CVE-2021-42321","title":"7BitsTeam/exch_CVE-2021-42321","date":"2022-10-08","url":"https://github.com/7BitsTeam/exch_CVE-2021-42321"}],"products":[{"vendor":"microsoft","product":"exchange"},{"vendor":"microsoft","product":"exchange_server"},{"vendor":"microsoft","product":"microsoft exchange server 2016 cumulative update 21"},{"vendor":"microsoft","product":"microsoft exchange server 2016 cumulative update 22"},{"vendor":"microsoft","product":"microsoft exchange server 2019 cumulative update 10"},{"vendor":"microsoft","product":"microsoft exchange server 2019 cumulative update 11"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42321","tags":["vendor-advisory","patch","Patch","Vendor Advisory"]},{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321","tags":["x_refsource_MISC","x_transferred","Patch","Vendor Advisory"]},{"url":"http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.html","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory","VDB Entry"]},{"url":"http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.html","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory","VDB Entry"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42321","tags":["government-resource","US Government Resource"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-42321"},{"url":"https://github.com/advisories/GHSA-3f87-66x4-f3p7"}],"sources":{"cve":[{"id":"CVE-2021-42321","title":"Microsoft Exchange Server Remote Code Execution Vulnerability","description":"Microsoft Exchange Server Remote Code Execution Vulnerability","status":"published","published":"2021-11-10T00:47:43Z","modified":"2026-08-19T16:27:07.165Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high","assessor":"cna"}],"updated_at":"2026-11-02T14:32:58.739039Z"}],"euvd":[{"id":"EUVD-2021-29296","description":"Microsoft Exchange Server Remote Code Execution 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execution.","cwes":["CWE-184","CWE-502"],"kev":{"date_added":"2021-11-17","due_date":"2021-12-01","required_action":"Apply updates per vendor instructions.","known_ransomware_use":"Known"},"updated_at":"2026-11-02T17:00:16.541131Z"}],"nvd":[{"id":"CVE-2021-42321","description":"Microsoft Exchange Server Remote Code Execution Vulnerability","status":"published","published":"2021-11-10T01:19:50.047Z","modified":"2026-08-19T19:23:07.277Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"},{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"},{"version":"2.0","score":6.5,"vector":"AV:N/AC:L/Au:S/C:P/I:P/A:P","level":"medium","assessor":"primary"}],"updated_at":"2026-11-02T14:07:00.984108Z"}]}}