{"id":"CVE-2021-41357","kind":"vulnerability","aliases":["CVE-2021-41357"],"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 graphics driver, contains an unspecified flaw that lets a local user raise their privileges. Attackers exploit it in the wild, so a low-privileged foothold on a Windows machine can become full control of that 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","microsoft-windows","windows"],"not_affected_if":["patched-windows"],"how_to_check":null,"fix":"Apply the Microsoft security update for CVE-2021-41357 per vendor instructions, as CISA requires.","status":"open","published_at":"2021-10-13T01:15:13+00:00","first_seen_at":"2026-10-23T19:11:52+00:00","triaged_at":"2026-10-23T21:17:43+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T21:17:43Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft security update for CVE-2021-41357 per vendor instructions, as CISA requires.\nunknown","reach":"local","impact":"high","summary":"Microsoft Win32k, the Windows kernel graphics driver, contains an unspecified flaw that lets a local user raise their privileges. Attackers exploit it in the wild, so a low-privileged foothold on a Windows machine can become full control of that machine.","category":"infrastructure","who_cares":["windows","microsoft-windows"],"confidence":0.6,"needs_auth":"yes","worst_case":"local user gains SYSTEM privileges on the Windows machine","analyst_note":"Find the Microsoft Security Response Center advisory for CVE-2021-41357 to get affected Windows builds, the patch KB numbers and a detection method.","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":0.000459,"input_tokens":2813,"output_tokens":356,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':9A,12A '-41357':10A,13A 'action':77C 'allow':71C 'appli':78C 'attack':41B 'becom':58B 'cisa':75C 'contain':29B,66C 'control':60B 'cve':8A,11A 'driver':28B 'escal':6A,74C 'exploit':16B,42B 'flaw':32B 'foothold':52B 'full':59B 'graphic':27B 'infrastructur':17B 'instruct':82C 'kernel':26B 'let':34B 'local':36B 'low':50B 'low-privileg':49B 'machin':56B,63B 'microsoft':1A,3A,14A,19B,22B,64C 'microsoft-window':18B 'per':80C 'privileg':5A,40B,51B,73C 'rais':38B 'requir':76C 'unspecifi':31B,68C 'updat':79C 'user':37B 'vendor':81C 'vulner':7A,69C 'wild':46B 'win32k':2A,4A,15A,23B,65C 'window':20B,21B,25B,55B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-10-13T01:15:13+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-2021-41357","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-41357","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":"2026-10-25T12:39:24+00:00","note":null},{"source":"epss","external_id":"CVE-2021-41357","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-41357","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-2021-41357","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-41357","severity":null,"published_at":"2021-10-13T01:15:13+00:00","modified_at":"2026-06-17T04:08:24+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"}