CVE-2026-21509

{"id": "CVE-2026-21509", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "secure@microsoft.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 1.8}]}, "published": "2026-01-26T18:16:38.540", "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509", "tags": ["Vendor Advisory"], "source": "secure@microsoft.com"}, {"url": "https://www.vicarius.io/vsociety/posts/cve-2026-21509-detection-script-microsoft-office-security-feature-bypass-vulnerability", "tags": ["Third Party Advisory"], "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://www.vicarius.io/vsociety/posts/cve-2026-21509-mitigation-script-microsoft-office-security-feature-bypass-vulnerability", "tags": ["Mitigation", "Third Party Advisory"], "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509", "tags": ["US Government Resource"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "secure@microsoft.com", "description": [{"lang": "en", "value": "CWE-807"}]}], "descriptions": [{"lang": "en", "value": "Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally."}, {"lang": "es", "value": "Dependencia de entradas no confiables en una decisi\u00f3n de seguridad en Microsoft Office permite a un atacante no autorizado eludir una caracter\u00edstica de seguridad localmente."}], "lastModified": "2026-02-11T15:40:33.473", "cisaActionDue": "2026-02-16", "cisaExploitAdd": "2026-01-26", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*", "vulnerable": true, "matchCriteriaId": "3259EBFE-AE2D-48B8-BE9A-E22BBDB31378"}, {"criteria": "cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*", "vulnerable": true, "matchCriteriaId": "CD25F492-9272-4836-832C-8439EBE64CCF"}, {"criteria": "cpe:2.3:a:microsoft:office:2016:*:*:*:*:*:x64:*", "vulnerable": true, "matchCriteriaId": "72324216-4EB3-4243-A007-FEF3133C7DF9"}, {"criteria": "cpe:2.3:a:microsoft:office:2016:*:*:*:*:*:x86:*", "vulnerable": true, "matchCriteriaId": "0FBB0E61-7997-4F26-9C07-54912D3F1C10"}, {"criteria": "cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x64:*", "vulnerable": true, "matchCriteriaId": "CF5DDD09-902E-4881-98D0-CB896333B4AA"}, {"criteria": "cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x86:*", "vulnerable": true, "matchCriteriaId": "26A3B226-5D7C-4556-9350-5222DC8EFC2C"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x64:*", "vulnerable": true, "matchCriteriaId": "851BAC4E-9965-4F40-9A6C-B73D9004F4C1"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x86:*", "vulnerable": true, "matchCriteriaId": "23B2FA23-76F4-4D83-A718-B8D04D7EA37B"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x64:*", "vulnerable": true, "matchCriteriaId": "D31E509A-0B2E-4B41-88C4-0099E800AFE6"}, {"criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x86:*", "vulnerable": true, "matchCriteriaId": "017A7041-BEF1-4E4E-AC8A-EFC6AFEB01FE"}], "operator": "OR"}]}], "sourceIdentifier": "secure@microsoft.com", "cisaRequiredAction": "Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.", "cisaVulnerabilityName": "Microsoft Office Security Feature Bypass Vulnerability"}