{"id":"CVE-2021-40450","kind":"vulnerability","aliases":["CVE-2021-40450"],"related":[],"title":"Microsoft Win32k: Microsoft Win32k Privilege Escalation Vulnerability","description":"Microsoft Win32k contains an unspecified vulnerability that allows for privilege escalation.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Microsoft Win32k, the Windows kernel-mode graphics subsystem, contains a flaw that lets a local user escalate privileges. Attackers exploit it in the wild, so a low-privilege foothold can become full control of the Windows machine.","severity":"high","cvss":7.8,"epss":0.01582,"exploited":true,"exploited_at":"2022-04-25T00:00:00+00:00","products":[{"name":"Microsoft Win32k","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","infrastructure","self-hosted","windows"],"not_affected_if":["fully-patched-windows"],"how_to_check":null,"fix":"Apply the Microsoft security update for CVE-2021-40450 per vendor instructions (CISA required action); the specific patched build is unknown from the sources.","status":"open","published_at":"2021-10-13T01:15:09+00:00","first_seen_at":"2026-10-23T19:11:52+00:00","triaged_at":"2026-10-23T21:17:44+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T21:17:44Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft security update for CVE-2021-40450 per vendor instructions (CISA required action); the specific patched build is unknown from the sources.","reach":"local","impact":"high","summary":"Microsoft Win32k, the Windows kernel-mode graphics subsystem, contains a flaw that lets a local user escalate privileges. Attackers exploit it in the wild, so a low-privilege foothold can become full control of the Windows machine.","category":"infrastructure","who_cares":["windows","self-hosted"],"confidence":0.6,"needs_auth":"yes","worst_case":"local user gains SYSTEM privileges on the Windows machine","analyst_note":"Confirm patched Windows builds and KB article from the Microsoft advisory for CVE-2021-40450 and add a concrete how_to_check.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["fully-patched-windows"],"user_interaction":"no","needs_special_setup":"no","severity_if_unknown":"high"},"cost_usd":0.000461,"input_tokens":2813,"output_tokens":359,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':9A,12A '-40450':10A,13A 'action':74C 'allow':68C 'appli':75C 'attack':41B 'becom':54B 'cisa':72C 'contain':31B,63C 'control':56B 'cve':8A,11A 'escal':6A,39B,71C 'exploit':16B,42B 'flaw':33B 'foothold':52B 'full':55B 'graphic':29B 'host':20B 'infrastructur':17B 'instruct':79C 'kernel':27B 'kernel-mod':26B 'let':35B 'local':37B 'low':50B 'low-privileg':49B 'machin':60B 'microsoft':1A,3A,14A,22B,61C 'mode':28B 'per':77C 'privileg':5A,40B,51B,70C 'requir':73C 'self':19B 'self-host':18B 'subsystem':30B 'unspecifi':65C 'updat':76C 'user':38B 'vendor':78C 'vulner':7A,66C 'wild':46B 'win32k':2A,4A,15A,23B,62C 'window':21B,25B,59B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-10-13T01:15:09+00:00","kev":{"dateAdded":"2022-04-25","dueDate":"2022-05-16","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-2021-40450","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-40450","severity":null,"published_at":"2022-04-25T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:52+00:00","fetched_at":"2026-10-25T14:39:40+00:00","note":null},{"source":"epss","external_id":"CVE-2021-40450","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-40450","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:45+00:00","fetched_at":"2026-10-23T19:13:45+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-40450","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-40450","severity":null,"published_at":"2021-10-13T01:15:09+00:00","modified_at":"2026-06-17T04:06:56+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"}