{"id":"CVE-2021-31979","kind":"vulnerability","aliases":["CVE-2021-31979"],"related":[],"title":"Microsoft Windows: Microsoft Windows Kernel Privilege Escalation Vulnerability","description":"Microsoft Windows kernel contains an unspecified vulnerability that allows for privilege escalation.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Microsoft Windows kernel has an unspecified flaw that lets a local user raise their privileges. An attacker with a low-privilege account on the machine can gain SYSTEM-level control.","severity":"high","cvss":7.8,"epss":0.0454,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Microsoft Windows","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","infrastructure","self-hosted","windows"],"not_affected_if":["patched-windows"],"how_to_check":null,"fix":"Apply the Microsoft Windows security update per vendor instructions (CISA required action); the specific KB or build number is not in the sources.","status":"open","published_at":"2021-07-14T18:15:09+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:39:29+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T21:39:29Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft Windows security update per vendor instructions (CISA required action); the specific KB or build number is not in the sources.\nunknown","reach":"local","impact":"high","summary":"Microsoft Windows kernel has an unspecified flaw that lets a local user raise their privileges. An attacker with a low-privilege account on the machine can gain SYSTEM-level control.","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":"Find the affected Windows builds and the patch KB from the Microsoft security update guide for CVE-2021-31979; sources do not list versions.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["patched-windows"],"user_interaction":"no","needs_special_setup":"no","severity_if_unknown":"high"},"cost_usd":0.000448,"input_tokens":2816,"output_tokens":333,"severity_before":"unknown"},"analyst_status":"queued","analyst_note":"Find the affected Windows builds and the patch KB from the Microsoft security update guide for CVE-2021-31979; sources do not list versions.","search":"'-2021':10A,13A '-31979':11A,14A 'account':45B 'action':69C 'allow':63C 'appli':70C 'attack':39B 'cisa':67C 'contain':58C 'control':54B 'cve':9A,12A 'escal':7A,66C 'exploit':17B 'flaw':29B 'gain':50B 'host':21B 'infrastructur':18B 'instruct':74C 'kernel':5A,25B,57C 'let':31B 'level':53B 'local':33B 'low':43B 'low-privileg':42B 'machin':48B 'microsoft':1A,3A,15A,23B,55C 'per':72C 'privileg':6A,37B,44B,65C 'rais':35B 'requir':68C 'self':20B 'self-host':19B 'system':52B 'system-level':51B 'unspecifi':28B,60C 'updat':71C 'user':34B 'vendor':73C 'vulner':8A,61C 'window':2A,4A,22B,24B,56C 'windows':16A","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-07-14T18:15:09+00:00","kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","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-2021-31979","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-31979","severity":null,"published_at":"2021-11-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T12:39:25+00:00","note":null},{"source":"epss","external_id":"CVE-2021-31979","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-31979","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-2021-31979","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-31979","severity":null,"published_at":"2021-07-14T18:15:09+00:00","modified_at":"2026-08-10T19:58:41+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"}