{"id":"CVE-2021-34486","published":"2021-08-12T18:15:09Z","modified":"2026-08-10T19:59:11Z","title":"Microsoft Windows Event Tracing Privilege Escalation Vulnerability","vendor":"Microsoft","product":"Windows","tier":"core","eol":null,"description":{"text":"Windows Event Tracing Elevation of Privilege Vulnerability","provenance":"source","from":"NVD"},"summary":{"text":"The flaw is a use-after-free weakness in the Windows Event Tracing component of Microsoft Windows, which allows privilege escalation. An attacker with local access and low-privileged credentials, requiring no user interaction, can exploit it to gain elevated privileges on the affected system.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:13:34Z"},"cvss":{"score":7.8,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.09328,"percentile":0.95368,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2022-03-28","dueDate":"2022-04-18","ransomware":false,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-34486","provenance":"source"},"vulncheckKev":{"dateAdded":"2022-03-28","exploitedFirstSeen":"2022-03-28","ransomware":false,"evidence":[{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2022-03-28"}],"evidenceTotal":1,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"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"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-416","name":"Use After Free"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34486","tags":["Patch","Vendor Advisory"]},{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34486","tags":["Patch","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34486","tags":["US Government Resource"]}],"techniques":[{"id":"T1068","name":"Exploitation for Privilege Escalation","tactics":["privilege-escalation"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Local attacker elevates privileges via kernel flaw","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"Windows Event Tracing Elevation of Privilege Vulnerability","start":0,"end":58}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-21140","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-21140","exploited":true,"exploitedSince":"2022-03-28","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":1,"skipped":1,"earliest":"2021-10-12","earliestUrl":"https://github.com/KaLendsi/CVE-2021-34486","repos":[{"name":"KaLendsi/CVE-2021-34486","url":"https://github.com/KaLendsi/CVE-2021-34486","stars":51,"created":"2021-10-12"}]},"first":{"date":"2021-10-12","source":"PoC-in-GitHub","url":"https://github.com/KaLendsi/CVE-2021-34486"},"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1068"],"provenance":"ai"}],"timeline":[{"date":"2021-08-12","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-34486","provenance":"source"},{"date":"2021-10-12","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub","url":"https://github.com/KaLendsi/CVE-2021-34486","provenance":"source"},{"date":"2022-03-28","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","provenance":"source"},{"date":"2022-03-28","kind":"kev","label":"Added to CISA KEV","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2022-03-28","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-21140","provenance":"source"}],"speed":{"daysToPublicExploit":61,"firstExploitFrom":"PoC-in-GitHub","daysToKev":228},"priority":{"score":67.5,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":0.0,"detail":"added 1676 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":19.07,"detail":"percentile 0.9537"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":5.0,"detail":"1 PoC-in-GitHub repo"},{"name":"Mentioned in OTX pulses","points":3.0,"detail":"50 pulses"},{"name":"CVSS severity","points":5.46,"detail":"base score 7.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]},"lineage":{"familyId":"fam-class-microsoft-windows-cwe-416"}}