{"id":"CVE-2021-33739","kind":"vulnerability","aliases":["CVE-2021-33739"],"related":[],"title":"Microsoft Windows: Microsoft Desktop Window Manager (DWM) Core Library Privilege Escalation Vulnerability","description":"Microsoft Desktop Window Manager (DWM) Core Library contains an unspecified vulnerability that allows for privilege escalation.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Microsoft Desktop Window Manager (DWM) Core Library has a flaw that lets a local user raise their privileges. Exploitation of this bug is confirmed in the wild, per CISA's Known Exploited Vulnerabilities catalog.","severity":"high","cvss":8.4,"epss":0.06555,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Microsoft Windows","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","infrastructure","windows"],"not_affected_if":[],"how_to_check":null,"fix":"Apply the Microsoft Windows update that addresses CVE-2021-33739 per vendor instructions, as CISA requires.","status":"open","published_at":"2021-06-08T23:15:09+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:37:32+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T21:37:32Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft Windows update that addresses CVE-2021-33739 per vendor instructions, as CISA requires.\nunknown","reach":"local","impact":"high","summary":"Microsoft Desktop Window Manager (DWM) Core Library has a flaw that lets a local user raise their privileges. Exploitation of this bug is confirmed in the wild, per CISA's Known Exploited Vulnerabilities catalog.","category":"infrastructure","who_cares":["windows"],"confidence":0.6,"needs_auth":"yes","worst_case":"Local attacker gains elevated system privileges on the Windows machine.","analyst_note":"Sources give no affected or fixed Windows build numbers; check Microsoft's CVE-2021-33739 security update guide entry for the patched builds and a detection method.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":[],"user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.00046,"input_tokens":2839,"output_tokens":353,"severity_before":"unknown"},"analyst_status":"queued","analyst_note":"Sources give no affected or fixed Windows build numbers; check Microsoft's CVE-2021-33739 security update guide entry for the patched builds and a detection method.","search":"'-2021':14A,17A '-33739':15A,18A 'action':76C 'allow':70C 'appli':77C 'bug':45B 'catalog':57B 'cisa':52B,74C 'confirm':47B 'contain':65C 'core':8A,29B,63C 'cve':13A,16A 'desktop':4A,25B,59C 'dwm':7A,28B,62C 'escal':11A,73C 'exploit':21B,42B,55B 'flaw':33B 'infrastructur':22B 'instruct':81C 'known':54B 'let':35B 'librari':9A,30B,64C 'local':37B 'manag':6A,27B,61C 'microsoft':1A,3A,19A,24B,58C 'per':51B,79C 'privileg':10A,41B,72C 'rais':39B 'requir':75C 'unspecifi':67C 'updat':78C 'user':38B 'vendor':80C 'vulner':12A,56B,68C 'wild':50B 'window':2A,5A,23B,26B,60C 'windows':20A","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-06-08T23:15:09+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:N/UI:N/S:U/C:H/I:H/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-33739","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-33739","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":"2026-10-25T19:35:26+00:00","note":null},{"source":"epss","external_id":"CVE-2021-33739","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-33739","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-2021-33739","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-33739","severity":null,"published_at":"2021-06-08T23:15:09+00:00","modified_at":"2026-06-17T03:55:08+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"}