{"id":"CVE-2026-21514","published":"2026-02-10T18:16:33Z","modified":"2026-06-17T10:18:45Z","title":"Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision Vulnerability","vendor":"Microsoft","product":"Office","tier":"core","eol":null,"description":{"text":"Reliance on untrusted inputs in a security decision in Microsoft Office Word allows an unauthorized attacker to bypass a security feature locally.","provenance":"source","from":"NVD"},"summary":{"text":"Microsoft Office Word contains a flaw in which the application relies on untrusted inputs when making a security decision. An unauthorized attacker with local access can bypass a security feature, and exploitation requires user interaction.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:14:37Z"},"cvss":{"score":7.8,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.01587,"percentile":0.75584,"date":"2026-10-30","provenance":"source"},"kev":{"dateAdded":"2026-02-10","dueDate":"2026-03-03","ransomware":false,"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.","notes":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21514 ; https://nvd.nist.gov/vuln/detail/CVE-2026-21514","provenance":"source"},"vulncheckKev":{"dateAdded":"2026-02-10","exploitedFirstSeen":"2026-02-10","ransomware":false,"evidence":[{"url":"https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2026-Feb","date":"2026-02-10"},{"url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","date":"2026-02-10"},{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21514","date":"2026-02-10"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2026-02-10"},{"url":"https://www.rapid7.com/blog/post/tr-detection-coverage-iran-linked-cyber-activity/","date":"2026-03-11"},{"url":"https://www.recordedfuture.com/blog/february-2026-cve-landscape","date":"2026-03-12"},{"url":"https://view.bitsight.com/viewer/275c18689811d887dfa0368866323ed5#1","date":"2026-06-22"},{"url":"https://ti.qianxin.com/uploads/2026/10/29/20ab59a356a884498644cff73d47a13a.pdf","date":"2026-10-29"}],"evidenceTotal":8,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 31, 2026","url":"https://otx.alienvault.com/pulse/6ae4aefab0c2191cecd41862","created":"2026-10-30"},{"name":"Actively_Exploited_Kev | Oct 30, 2026","url":"https://otx.alienvault.com/pulse/6ae35d889ea92b4ce19c2680","created":"2026-10-29"},{"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"}],"provenance":"machine"},"cwes":[{"id":"CWE-807","name":"Reliance on Untrusted Inputs in a Security Decision"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21514","tags":["Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21514","tags":["US Government Resource"]}],"techniques":[{"id":"T1204.002","name":"Malicious File","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Local user opens crafted Word document","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"allows an unauthorized attacker to bypass a security feature locally","start":77,"end":145}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1211","name":"Exploitation for Stealth","tactics":["stealth"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Bypasses Office security feature","mappingType":"primary_impact","evidence":[{"from":"description","quote":"allows an unauthorized attacker to bypass a security feature","start":77,"end":137}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2026-7334","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-7334","exploited":true,"exploitedSince":"2026-02-10","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":1,"skipped":0,"earliest":"2026-05-04","earliestUrl":"https://github.com/ChaitanyaHaritash/CVE-2026-21514_CVE-2026-21510","repos":[{"name":"ChaitanyaHaritash/CVE-2026-21514_CVE-2026-21510","url":"https://github.com/ChaitanyaHaritash/CVE-2026-21514_CVE-2026-21510","stars":7,"created":"2026-05-04"}]},"first":{"date":"2026-05-04","source":"PoC-in-GitHub","url":"https://github.com/ChaitanyaHaritash/CVE-2026-21514_CVE-2026-21510"},"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1204.002"],"provenance":"ai"},{"stage":"primary","techniques":["T1211"],"provenance":"ai"}],"timeline":[{"date":"2026-02-10","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21514","provenance":"source"},{"date":"2026-02-10","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2026-Feb","provenance":"source"},{"date":"2026-02-10","kind":"kev","label":"Added to CISA KEV","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2026-02-10","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-7334","provenance":"source"},{"date":"2026-05-04","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub","url":"https://github.com/ChaitanyaHaritash/CVE-2026-21514_CVE-2026-21510","provenance":"source"}],"speed":{"daysToPublicExploit":83,"firstExploitFrom":"PoC-in-GitHub","daysToKev":0},"priority":{"score":68.6,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck 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