{"id":"CVE-2021-34486","kind":"vulnerability","aliases":["CVE-2021-34486"],"related":[],"title":"Microsoft Windows: Microsoft Windows Event Tracing Privilege Escalation Vulnerability","description":"Microsoft Windows Event Tracing contains an unspecified vulnerability which can allow for privilege escalation.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Microsoft Windows Event Tracing has a flaw that lets a local user escalate privileges on the machine. An attacker with a low-privilege foothold can gain SYSTEM-level control, and CISA lists it as actively exploited.","severity":"high","cvss":7.8,"epss":0.09253,"exploited":true,"exploited_at":"2022-03-28T00:00:00+00:00","products":[{"name":"Microsoft Windows","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","infrastructure","self-hosted","windows"],"not_affected_if":["patched-windows-build"],"how_to_check":"Check the installed Windows build against Microsoft's CVE-2021-34486 advisory (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34486) and confirm the August 2021 security update is installed.","fix":"Install the Microsoft security update for CVE-2021-34486 from August 2021 or later via Windows Update.","status":"open","published_at":"2021-08-12T18:15:09+00:00","first_seen_at":"2026-10-23T19:11:52+00:00","triaged_at":"2026-10-23T21:19:56+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T21:19:56Z","model":"claude-haiku-5-5","output":{"fix":"Install the Microsoft security update for CVE-2021-34486 from August 2021 or later via Windows Update.\nunknown","reach":"local","impact":"high","summary":"Microsoft Windows Event Tracing has a flaw that lets a local user escalate privileges on the machine. An attacker with a low-privilege foothold can gain SYSTEM-level control, and CISA lists it as actively exploited.","category":"infrastructure","who_cares":["windows","self-hosted"],"confidence":0.6,"needs_auth":"yes","worst_case":"Local attacker gains SYSTEM privileges on the Windows machine.","analyst_note":"Confirm the exact affected Windows builds and the patch KB numbers from the Microsoft MSRC advisory for CVE-2021-34486.","how_to_check":"Check the installed Windows build against Microsoft's CVE-2021-34486 advisory (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34486) and confirm the August 2021 security update is installed.\nunknown","needs_analyst":true,"not_affected_if":["patched-windows-build"],"user_interaction":"no","needs_special_setup":"no","severity_if_unknown":"high"},"cost_usd":0.000497,"input_tokens":2822,"output_tokens":429,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':11A,14A '-34486':12A,15A 'action':78C 'activ':60B 'allow':72C 'appli':79C 'attack':42B 'cisa':56B,76C 'contain':66C 'control':54B 'cve':10A,13A 'escal':8A,36B,75C 'event':5A,26B,64C 'exploit':18B,61B 'flaw':30B 'foothold':48B 'gain':50B 'host':22B 'infrastructur':19B 'instruct':83C 'let':32B 'level':53B 'list':57B 'local':34B 'low':46B 'low-privileg':45B 'machin':40B 'microsoft':1A,3A,16A,24B,62C 'per':81C 'privileg':7A,37B,47B,74C 'requir':77C 'self':21B 'self-host':20B 'system':52B 'system-level':51B 'trace':6A,27B,65C 'unspecifi':68C 'updat':80C 'user':35B 'vendor':82C 'vulner':9A,69C 'window':2A,4A,23B,25B,63C 'windows':17A","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-08-12T18:15:09+00:00","kev":{"dateAdded":"2022-03-28","dueDate":"2022-04-18","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-34486","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-34486","severity":null,"published_at":"2022-03-28T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:52+00:00","fetched_at":"2026-10-25T13:39:31+00:00","note":null},{"source":"epss","external_id":"CVE-2021-34486","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-34486","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:44+00:00","fetched_at":"2026-10-23T19:13:44+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-34486","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-34486","severity":null,"published_at":"2021-08-12T18:15:09+00:00","modified_at":"2026-08-10T19:59:11+00:00","first_seen_at":"2026-10-23T21:57:35+00:00","fetched_at":"2026-10-23T21:57:35+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"}