{"cveID":"CVE-2021-42321","vendorProject":"Microsoft","product":"Exchange","vulnerabilityName":"Microsoft Exchange Server Remote Code Execution Vulnerability","dateAdded":"2021-11-17","shortDescription":"An authenticated attacker could leverage improper validation in cmdlet arguments within Microsoft Exchange and perform remote code execution.","requiredAction":"Apply updates per vendor instructions.","dueDate":"2021-12-01","knownRansomwareCampaignUse":"Known","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-42321","cwes":["CWE-184","CWE-502"],"year":2021,"state":"mapped","stale_reasons":[],"mappings":[{"domain":"enterprise","cve":"CVE-2021-42321","technique":"T1078","technique_name_at_mapping":"Valid Accounts","mapping_type":"exploitation_technique","capability_group":"code_execution","comments":"This vulnerability is exploited by an adversary who has gained authentication to the Exchange Server and exploited validation issues in command-let arguments. This gives the adversary access to perform remote code execution on the server. ","references":["https://www.bleepingcomputer.com/news/security/exploit-released-for-microsoft-exchange-rce-bug-patch-now/","https://techcommunity.microsoft.com/blog/exchange/released-november-2021-exchange-server-security-updates/2933169","https://threatpost.com/microsoft-nov-patch-tuesday-fixes-six-zero-days-55-bugs/176143/"],"status":"complete","source_file":"kev-07.28.2025_attack-16.1-enterprise.json","attack_version":"16.1","kev_snapshot":"07/28/2025"},{"domain":"enterprise","cve":"CVE-2021-42321","technique":"T1059","technique_name_at_mapping":"Command and Scripting Interpreter","mapping_type":"primary_impact","capability_group":"code_execution","comments":"This vulnerability is exploited by an adversary who has gained authentication to the Exchange Server and exploited validation issues in command-let arguments. This gives the adversary access to perform remote code execution on the server. ","references":["https://techcommunity.microsoft.com/blog/exchange/released-november-2021-exchange-server-security-updates/2933169","https://threatpost.com/microsoft-nov-patch-tuesday-fixes-six-zero-days-55-bugs/176143/"],"status":"complete","source_file":"kev-07.28.2025_attack-16.1-enterprise.json","attack_version":"16.1","kev_snapshot":"07/28/2025"}],"techniques":[{"id":"T1059","domains":["enterprise"],"in_current_bundle":true,"live":true,"name_now":"Command and Scripting Interpreter","name_at_mapping":"Command and Scripting Interpreter","renamed":false,"revoked_by":null,"mapping_types":["primary_impact"],"sigma_rule_count":95,"has_detection_strategy":true},{"id":"T1078","domains":["enterprise"],"in_current_bundle":true,"live":true,"name_now":"Valid Accounts","name_at_mapping":"Valid Accounts","renamed":false,"revoked_by":null,"mapping_types":["exploitation_technique"],"sigma_rule_count":56,"has_detection_strategy":true}],"mapping_types":["exploitation_technique","primary_impact"],"has_exploitation_technique":true,"mapping_attack_versions":["16.1"],"mapping_domains":["enterprise"],"sigma_coverage":"full","sigma_rules_tagged_cve":[],"added_after_mapping_snapshot":false,"_source":"kevmap","_built":"2026-08-24 19:45 UTC","_attack_version":"19.2"}