{"id":"CVE-2026-21514","kind":"vulnerability","aliases":["CVE-2026-21514"],"related":[],"title":"Reliance on untrusted inputs in a security decision in Microsoft Office Word allows an unauthorized attacker to…","description":"Microsoft Office Word contains a reliance on untrusted inputs in a security decision vulnerability that could allow an authorized attacker to elevate privileges locally.\n\nCISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","summary":"Microsoft Office Word has a flaw where it relies on untrusted input when making a security decision. An authorized local user can use it to elevate their privileges, and CISA reports it is being exploited in the wild.","severity":"high","cvss":7.8,"epss":null,"exploited":true,"exploited_at":"2026-02-10T00:00:00+00:00","products":[{"name":"Microsoft Office","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"microsoft 365 apps","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"microsoft office long term servicing channel","fixed":[],"affected":"= 2021","ecosystem":"vendor"},{"name":"microsoft office long term servicing channel","fixed":[],"affected":"= 2024","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","microsoft-office","microsoft-word","other","windows"],"not_affected_if":["unknown"],"how_to_check":"Check the installed Microsoft Office Word build against Microsoft's security update guide for CVE-2026-21514; the sources do not give the affected build numbers.","fix":"Apply the Microsoft security update for CVE-2026-21514 per vendor instructions; if no mitigation is available, discontinue use of the product as CISA directs (sources do not name the patched version).","status":"open","published_at":"2026-02-10T00:00:00+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:42:23+00:00","updated_at":"2026-10-23T23:44:51+00:00","category":"other","confidence":0.6,"triage":{"at":"2026-10-23T20:42:23Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft security update for CVE-2026-21514 per vendor instructions; if no mitigation is available, discontinue use of the product as CISA directs (sources do not name the patched version).","reach":"local","summary":"Microsoft Office Word has a flaw where it relies on untrusted input when making a security decision. An authorized local user can use it to elevate their privileges, and CISA reports it is being exploited in the wild.","category":"other","who_cares":["microsoft-office","microsoft-word","windows"],"confidence":0.6,"needs_auth":"yes","worst_case":"Local attacker with an account gains elevated privileges on the affected machine.","analyst_note":"Find the affected and fixed Word build numbers and the mitigation steps in Microsoft's security update guide for CVE-2026-21514; sources only give the KEV entry.","how_to_check":"Check the installed Microsoft Office Word build against Microsoft's security update guide for CVE-2026-21514; the sources do not give the affected build numbers.","needs_analyst":true,"not_affected_if":["unknown"],"user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.00046,"input_tokens":2543,"output_tokens":412,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-01':123C '-2026':18A,21A '-21514':19A,22A '22':122C '365':26A 'action':113C 'allow':13A,103C 'appli':114C 'applic':120C 'apps':27A 'attack':16A,106C 'author':67B,105C 'bod':121C 'channel':33A,39A 'cisa':78B,111C 'cloud':126C 'contain':90C 'could':102C 'cve':17A,20A 'decis':8A,65B,99C 'discontinu':129C 'elev':74B,108C 'exploit':40B,83B 'flaw':54B 'follow':119C 'guidanc':124C 'input':4A,60B,95C 'instruct':118C 'local':68B,110C 'long':30A,36A 'make':62B 'microsoft':10A,23A,25A,28A,34A,42B,45B,49B,87C 'microsoft-offic':41B 'microsoft-word':44B 'mitig':115C,135C 'offic':11A,43B,50B,88C 'office':24A,29A,35A 'per':116C 'privileg':76B,109C 'product':133C 'reli':57B 'relianc':1A,92C 'report':79B 'requir':112C 'secur':7A,64B,98C 'servic':127C 'servicing':32A,38A 'term':31A,37A 'unauthor':15A 'unavail':137C 'untrust':3A,59B,94C 'use':71B,130C 'user':69B 'vendor':117C 'vulner':100C 'wild':86B 'window':48B 'word':12A,46B,51B,89C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-02-10T00:00:00+00:00","kev":{"dateAdded":"2026-02-10","dueDate":"2026-03-03","requiredAction":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2026-21514","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-21514","severity":null,"published_at":"2026-02-10T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T13:39:29+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-21514","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21514","severity":null,"published_at":"2026-02-10T18:16:33+00:00","modified_at":"2026-06-17T10:18:45+00:00","first_seen_at":"2026-10-23T23:44:51+00:00","fetched_at":"2026-10-23T23:44:51+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"}