{"id":"CVE-2026-21510","published":"2026-02-10T18:16:33Z","modified":"2026-06-17T10:18:45Z","title":"Microsoft Windows Shell Protection Mechanism Failure Vulnerability","vendor":"Microsoft","product":"Windows","tier":"core","eol":null,"description":{"text":"Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.","provenance":"source","from":"NVD"},"summary":{"text":"The flaw is a protection mechanism failure in the Windows Shell component of Microsoft Windows. An unauthorized attacker over the network can bypass a security feature of Windows Shell, and exploitation requires user interaction.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:12:37Z"},"cvss":{"score":8.8,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.61238,"percentile":0.9916,"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-2026-21510 ; https://nvd.nist.gov/vuln/detail/CVE-2026-21510 ","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-2026-21510","date":"2026-02-10"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2026-02-10"},{"url":"https://www.recordedfuture.com/blog/february-2026-cve-landscape","date":"2026-03-12"},{"url":"https://www.akamai.com/blog/security-research/2026/apr/incomplete-patch-apt28s-zero-day-cve-2026-3220","date":"2026-04-23"},{"url":"https://www.proofpoint.com/us/blog/threat-insight/more-cves-same-playbook-2026-vulnerability-exploitation-wild","date":"2026-05-27"},{"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-693","name":"Protection Mechanism Failure"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21510","tags":["Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21510","tags":["US Government Resource"]}],"techniques":[{"id":"T1211","name":"Exploitation for Stealth","tactics":["stealth"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Bypasses a security feature via protection 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expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2026-7337","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-7337","exploited":true,"exploitedSince":"2026-02-10","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":2,"skipped":0,"earliest":"2026-02-11","earliestUrl":"https://github.com/andreassudo/CVE-2026-21510-CVSS-8.8-Important-Windows-Shell-security-feature-bypass","repos":[{"name":"andreassudo/CVE-2026-21510-CVSS-8.8-Important-Windows-Shell-security-feature-bypass","url":"https://github.com/andreassudo/CVE-2026-21510-CVSS-8.8-Important-Windows-Shell-security-feature-bypass","stars":7,"created":"2026-02-11"},{"name":"EpSiLoNPoInTOrI/EpSiLoNPoInTlnk","url":"https://github.com/EpSiLoNPoInTOrI/EpSiLoNPoInTlnk","stars":2,"created":"2026-05-09"}]},"first":{"date":"2026-02-11","source":"PoC-in-GitHub","url":"https://github.com/andreassudo/CVE-2026-21510-CVSS-8.8-Important-Windows-Shell-security-feature-bypass"},"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1211"],"provenance":"ai"},{"stage":"primary","techniques":["T1553"],"provenance":"ai"}],"timeline":[{"date":"2026-02-10","kind":"published","label":"Published 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