{"id":"CVE-2026-21533","kind":"vulnerability","aliases":["CVE-2026-21533"],"related":[],"title":"Improper privilege management in Windows Remote Desktop allows an authorized attacker to elevate privileges locally","description":"Microsoft Windows Remote Desktop Services contains an improper privilege management vulnerability that could allow an authorized attacker to elevate privileges locally.\n\nCISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","summary":"Windows Remote Desktop Services has an improper privilege management flaw that lets an authorized user raise their privileges on the machine. CISA lists it as actively exploited in the wild.","severity":"high","cvss":7.8,"epss":null,"exploited":true,"exploited_at":"2026-02-10T00:00:00+00:00","products":[{"name":"Microsoft Windows","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"microsoft windows 10 1607","fixed":["10.0.14393.8868"],"affected":"< 10.0.14393.8868","ecosystem":"vendor"},{"name":"microsoft windows 10 1809","fixed":["10.0.17763.8389"],"affected":"< 10.0.17763.8389","ecosystem":"vendor"},{"name":"microsoft windows 10 21h2","fixed":["10.0.19044.6937"],"affected":"< 10.0.19044.6937","ecosystem":"vendor"},{"name":"microsoft windows 10 22h2","fixed":["10.0.19045.6937"],"affected":"< 10.0.19045.6937","ecosystem":"vendor"},{"name":"microsoft windows 11 23h2","fixed":["10.0.22631.6649"],"affected":"< 10.0.22631.6649","ecosystem":"vendor"},{"name":"microsoft windows 11 24h2","fixed":["10.0.26100.7781"],"affected":"< 10.0.26100.7781","ecosystem":"vendor"},{"name":"microsoft windows 11 25h2","fixed":["10.0.26200.7781"],"affected":"< 10.0.26200.7781","ecosystem":"vendor"},{"name":"microsoft windows server 2012","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"microsoft windows server 2012","fixed":[],"affected":"= r2","ecosystem":"vendor"},{"name":"microsoft windows server 2016","fixed":["10.0.14393.8868"],"affected":"< 10.0.14393.8868","ecosystem":"vendor"},{"name":"microsoft windows server 2019","fixed":["10.0.17763.8389"],"affected":"< 10.0.17763.8389","ecosystem":"vendor"},{"name":"microsoft windows server 2022","fixed":["10.0.20348.4711"],"affected":"< 10.0.20348.4711","ecosystem":"vendor"},{"name":"microsoft windows server 2022 23h2","fixed":["10.0.25398.2149"],"affected":"< 10.0.25398.2149","ecosystem":"vendor"},{"name":"microsoft windows server 2025","fixed":["10.0.26100.32313"],"affected":"< 10.0.26100.32313","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","infrastructure","remote-desktop-services","windows"],"not_affected_if":["no-rds-hosts"],"how_to_check":null,"fix":"Apply the Microsoft security update for CVE-2026-21533 per vendor instructions; the sources do not name the patched build.","status":"open","published_at":"2026-02-10T00:00:00+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:42:23+00:00","updated_at":"2026-10-23T23:44:51+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T20:42:23Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft security update for CVE-2026-21533 per vendor instructions; the sources do not name the patched build.","reach":"local","summary":"Windows Remote Desktop Services has an improper privilege management flaw that lets an authorized user raise their privileges on the machine. CISA lists it as actively exploited in the wild.","category":"infrastructure","who_cares":["windows","remote-desktop-services"],"confidence":0.6,"needs_auth":"yes","worst_case":"A low-privilege authenticated user gains higher privileges, potentially SYSTEM, on the host.","analyst_note":"Find the Microsoft advisory for CVE-2026-21533 to confirm affected builds, patch KB, and any RDS-specific mitigation.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["no-rds-hosts"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000423,"input_tokens":2530,"output_tokens":339,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-01':151C '-2026':17A,20A '-21533':18A,21A '10':26A,30A,34A,38A '11':42A,46A,50A '1607':27A '1809':31A '2012':55A,59A '2016':63A '2019':67A '2022':71A,75A '2025':80A '21h2':35A '22':150C '22h2':39A '23h2':43A,76A '24h2':47A '25h2':51A 'action':141C 'activ':113B 'allow':8A,131C 'appli':142C 'applic':148C 'attack':11A,134C 'author':10A,101B,133C 'bod':149C 'cisa':109B,139C 'cloud':154C 'contain':123C 'could':130C 'cve':16A,19A 'desktop':7A,85B,90B,121C 'discontinu':157C 'elev':13A,136C 'exploit':81B,114B 'flaw':97B 'follow':147C 'guidanc':152C 'improp':1A,94B,125C 'infrastructur':82B 'instruct':146C 'let':99B 'list':110B 'local':15A,138C 'machin':108B 'manag':3A,96B,127C 'microsoft':22A,24A,28A,32A,36A,40A,44A,48A,52A,56A,60A,64A,68A,72A,77A,118C 'mitig':143C,163C 'per':144C 'privileg':2A,14A,95B,105B,126C,137C 'product':161C 'rais':103B 'remot':6A,84B,89B,120C 'remote-desktop-servic':83B 'requir':140C 'server':54A,58A,62A,66A,70A,74A,79A 'servic':86B,91B,122C,155C 'unavail':165C 'use':158C 'user':102B 'vendor':145C 'vulner':128C 'wild':117B 'window':5A,87B,88B,119C 'windows':23A,25A,29A,33A,37A,41A,45A,49A,53A,57A,61A,65A,69A,73A,78A","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-02-10T00:00:00+00:00","kev":{"dateAdded":"2026-02-10","dueDate":"2026-03-03","requiredAction":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","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-2026-21533","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-21533","severity":null,"published_at":"2026-02-10T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T11:39:14+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-21533","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21533","severity":null,"published_at":"2026-02-10T18:16:35+00:00","modified_at":"2026-06-17T10:18:47+00:00","first_seen_at":"2026-10-23T23:44:51+00:00","fetched_at":"2026-10-23T23:44:51+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"}