{"id":"CVE-2020-1040","kind":"vulnerability","aliases":["CVE-2020-1040"],"related":[],"title":"Microsoft Hyper-V RemoteFX: Microsoft Hyper-V RemoteFX vGPU Remote Code Execution Vulnerability","description":"Microsoft Hyper-V RemoteFX vGPU contains an improper input validation vulnerability due to the host server failing to properly validate input from an authenticated user on a guest operating system. Successful exploitation allows for remote code execution on the host operating system.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Microsoft Hyper-V RemoteFX vGPU mishandles input from an authenticated guest OS user, letting that guest run code on the Hyper-V host. Exploitation is listed by CISA as known to be used in the wild.","severity":"critical","cvss":9.0,"epss":0.07393,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Microsoft Hyper-V RemoteFX","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","hyper-v","infrastructure","virtualization","windows-server"],"not_affected_if":["no-hyper-v-remotefx","remotefx-vgpu-disabled"],"how_to_check":null,"fix":"Apply the Microsoft update for CVE-2020-1040 per vendor instructions (CISA KEV required action); the specific KB or patched build is not given in the sources.","status":"open","published_at":"2020-07-14T23:15:11+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:39:14+00:00","updated_at":"2026-10-23T21:57:34+00:00","category":"infrastructure","confidence":0.7,"triage":{"at":"2026-10-23T21:39:14Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft update for CVE-2020-1040 per vendor instructions (CISA KEV required action); the specific KB or patched build is not given in the sources.","reach":"local","impact":"high","summary":"Microsoft Hyper-V RemoteFX vGPU mishandles input from an authenticated guest OS user, letting that guest run code on the Hyper-V host. Exploitation is listed by CISA as known to be used in the wild.","category":"infrastructure","who_cares":["hyper-v","windows-server","virtualization"],"confidence":0.7,"needs_auth":"yes","worst_case":"Guest user runs code on the Hyper-V host operating system.","analyst_note":"Find the Microsoft security update guide entry for CVE-2020-1040 to get affected builds, the patch KB, and how to confirm RemoteFX vGPU is in use.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["no-hyper-v-remotefx","remotefx-vgpu-disabled"],"user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"high"},"cost_usd":0.000486,"input_tokens":2893,"output_tokens":394,"severity_before":"unknown"},"analyst_status":"queued","analyst_note":"Find the Microsoft security update guide entry for CVE-2020-1040 to get affected builds, the patch KB, and how to confirm RemoteFX vGPU is in use.","search":"'-1040':18A,21A '-2020':17A,20A 'action':119C 'allow':107C 'appli':120C 'authent':46B,98C 'cisa':65B,117C 'code':13A,54B,110C 'contain':80C 'cve':16A,19A 'due':86C 'execut':14A,111C 'exploit':27B,61B,106C 'fail':91C 'guest':47B,52B,102C 'host':60B,89C,114C 'hyper':3A,8A,24A,29B,38B,58B,76C 'hyper-v':2A,7A,23A,28B,37B,57B,75C 'improp':82C 'infrastructur':31B 'input':43B,83C,95C 'instruct':124C 'known':67B 'let':50B 'list':63B 'microsoft':1A,6A,22A,36B,74C 'mishandl':42B 'oper':103C,115C 'os':48B 'per':122C 'proper':93C 'remot':12A,109C 'remotefx':5A,10A,26A,40B,78C 'requir':118C 'run':53B 'server':35B,90C 'success':105C 'system':104C,116C 'updat':121C 'use':70B 'user':49B,99C 'v':4A,9A,25A,30B,39B,59B,77C 'valid':84C,94C 'vendor':123C 'vgpu':11A,41B,79C 'virtual':32B 'vulner':15A,85C 'wild':73B 'window':34B 'windows-serv':33B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2020-07-14T23:15:11+00:00","kev":{"dateAdded":"2021-11-03","dueDate":"2022-05-03","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2020-1040","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2020-1040","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":"2026-10-25T11:39:18+00:00","note":null},{"source":"epss","external_id":"CVE-2020-1040","url":"https://api.first.org/data/v1/epss?cve=CVE-2020-1040","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:43+00:00","fetched_at":"2026-10-23T19:13:43+00:00","note":null},{"source":"nvd","external_id":"CVE-2020-1040","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-1040","severity":null,"published_at":"2020-07-14T23:15:11+00:00","modified_at":"2026-06-17T03:00:17+00:00","first_seen_at":"2026-10-23T21:57:34+00:00","fetched_at":"2026-10-23T21:57:34+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"}