{"id":"CVE-2021-27059","kind":"vulnerability","aliases":["CVE-2021-27059"],"related":[],"title":"Microsoft Office: Microsoft Office Remote Code Execution Vulnerability","description":"Microsoft Office contains an unspecified vulnerability that allows for remote code execution.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Microsoft Office contains an unspecified flaw that allows remote code execution. CISA lists it in the Known Exploited Vulnerabilities catalog, so attackers are using it in real attacks.","severity":"high","cvss":8.5,"epss":0.06076,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Microsoft Office","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","microsoft-office","other","windows"],"not_affected_if":["unpatched-builds-only"],"how_to_check":"Check each Office install's version and patch level against Microsoft's security update guide for CVE-2021-27059. unknown for the exact affected build list.","fix":"Apply the Microsoft Office security updates per vendor instructions, as CISA requires. unknown for the specific patched build numbers.","status":"open","published_at":"2021-03-11T16:15:17+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:41:49+00:00","updated_at":"2026-10-23T21:57:34+00:00","category":"other","confidence":0.5,"triage":{"at":"2026-10-23T21:41:49Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft Office security updates per vendor instructions, as CISA requires. unknown for the specific patched build numbers.","reach":"unknown","impact":"high","summary":"Microsoft Office contains an unspecified flaw that allows remote code execution. CISA lists it in the Known Exploited Vulnerabilities catalog, so attackers are using it in real attacks.","category":"other","who_cares":["microsoft-office","windows"],"confidence":0.5,"needs_auth":"unknown","worst_case":"Attacker runs code on the victim's machine via a crafted Office file","analyst_note":"Find the affected and fixed Office build numbers and the attack vector (malicious document or network) on the Microsoft Security Update Guide page for CVE-2021-27059.","how_to_check":"Check each Office install's version and patch level against Microsoft's security update guide for CVE-2021-27059. unknown for the exact affected build list.","needs_analyst":true,"not_affected_if":["unpatched-builds-only"],"user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000476,"input_tokens":2804,"output_tokens":391,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':10A,13A '-27059':11A,14A 'action':65C 'allow':30B,58C 'appli':66C 'attack':44B,50B 'catalog':42B 'cisa':34B,63C 'code':6A,32B,61C 'contain':25B,53C 'cve':9A,12A 'execut':7A,33B,62C 'exploit':17B,40B 'flaw':28B 'instruct':70C 'known':39B 'list':35B 'microsoft':1A,3A,15A,19B,23B,51C 'microsoft-offic':18B 'offic':2A,4A,20B,24B,52C 'office':16A 'per':68C 'real':49B 'remot':5A,31B,60C 'requir':64C 'unspecifi':27B,55C 'updat':67C 'use':46B 'vendor':69C 'vulner':8A,41B,56C 'window':22B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-03-11T16:15:17+00:00","kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-27059","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-27059","severity":null,"published_at":"2021-11-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T12:39:25+00:00","note":null},{"source":"epss","external_id":"CVE-2021-27059","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-27059","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:43+00:00","fetched_at":"2026-10-23T19:13:43+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-27059","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-27059","severity":null,"published_at":"2021-03-11T16:15:17+00:00","modified_at":"2026-08-19T19:22:31+00:00","first_seen_at":"2026-10-23T21:57:34+00:00","fetched_at":"2026-10-23T21:57:34+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}