{"id":"CVE-2021-27059","published":"2021-03-11T16:15:17Z","modified":"2026-08-19T19:22:31Z","title":"Microsoft Office Remote Code Execution Vulnerability","vendor":"Microsoft","product":"Office","tier":"core","eol":null,"description":{"text":"Microsoft Office Remote Code Execution Vulnerability","provenance":"source","from":"NVD"},"summary":{"text":"The vulnerability is a remote code execution flaw in Microsoft Office, a product from Microsoft, though the available record does not identify the specific component involved. An attacker could execute code remotely over the network, but doing so requires high attack complexity, high-privilege authentication, and user interaction, with the potential to affect resources beyond the vulnerable component.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-29T07:11:27Z"},"cvss":{"score":7.6,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.06076,"percentile":0.93381,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","ransomware":false,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-27059","provenance":"source"},"vulncheckKev":{"dateAdded":"2021-03-12","exploitedFirstSeen":"2021-03-12","ransomware":false,"evidence":[{"url":"https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2021-Mar","date":"2021-03-12"},{"url":"https://twitter.com/blackorbird/status/1385062113085825027","date":"2021-04-21"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"}],"evidenceTotal":3,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-27059","tags":["Patch","Vendor Advisory"]},{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-27059","tags":["Patch","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27059","tags":["US Government Resource"]}],"techniques":[{"id":"T1203","name":"Exploitation for Client Execution","tactics":["execution"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Code Execution","mappingType":"exploitation_technique","evidence":[],"comment":"The vulnerability allows a remote user to execute arbitrary code on the target system due to improper input validation in Microsoft Office.","confidence":"medium","confidenceNote":"CTID KEV capability group \"code execution\" is generic"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-13830","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-13830","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1203"],"provenance":"source"}],"timeline":[{"date":"2021-03-11","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-27059","provenance":"source"},{"date":"2021-03-12","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2021-Mar","provenance":"source"},{"date":"2021-11-03","kind":"kev","label":"Added to CISA KEV","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2021-11-03","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-13830","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":237},"priority":{"score":62.0,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":0.0,"detail":"added 2057 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":18.68,"detail":"percentile 0.9338"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":0.0,"detail":"none found"},{"name":"Mentioned in OTX pulses","points":3.0,"detail":"50 pulses"},{"name":"CVSS severity","points":5.32,"detail":"base score 7.6"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}