{"id":"CVE-2026-121395","kind":"vulnerability","aliases":["CVE-2026-121395"],"related":[],"title":"FreeRDP: malicious RDP server can crash client via RemoteFX tile","description":"FreeRDP from 3.17.0 before 3.32.2 contains an assertion failure in the RemoteFX differential decoder when verbose WinPR assertions are enabled. A malicious RDP server can send a crafted RemoteFX tile with adjacent LL3 coefficients summing beyond signed 16-bit range to abort the client process.","summary":"FreeRDP's RemoteFX differential decoder fails an assertion when a malicious RDP server sends a crafted tile with out-of-range coefficients, aborting the client process. The sources describe a denial of service that only triggers when verbose WinPR assertions are enabled.","severity":"high","cvss":7.1,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["freerdp","linux","package","rdp","remotefx","windows"],"not_affected_if":["assertions-disabled","trusted-servers-only","versions-outside-3.17.0-to-3.32.2"],"how_to_check":"- Check the installed FreeRDP version, for example with `xfreerdp /version`, and compare it to the affected range `3.17.0` to before `3.32.2`.\n- Check whether verbose WinPR assertions are enabled in the build or the environment (unknown how to confirm from the sources).","fix":"- Move to FreeRDP `3.32.2` or later.","status":"open","published_at":"2026-11-03T15:17:27+00:00","first_seen_at":"2026-11-03T15:21:57+00:00","triaged_at":"2026-11-03T15:23:02+00:00","updated_at":"2026-11-03T15:23:02+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-03T15:23:02Z","model":"claude-haiku-5-5","output":{"fix":"- Move to FreeRDP `3.32.2` or later.","reach":"network","title":"FreeRDP: malicious RDP server can crash client via RemoteFX tile","impact":"low","summary":"FreeRDP's RemoteFX differential decoder fails an assertion when a malicious RDP server sends a crafted tile with out-of-range coefficients, aborting the client process. The sources describe a denial of service that only triggers when verbose WinPR assertions are enabled.","audience":"businesses","category":"package","nicknames":[],"who_cares":["freerdp","rdp","remotefx","linux","windows"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"Client process aborts, causing denial of service on the connecting machine.","analyst_note":"","how_to_check":"- Check the installed FreeRDP version, for example with `xfreerdp /version`, and compare it to the affected range `3.17.0` to before `3.32.2`.\n- Check whether verbose WinPR assertions are enabled in the build or the environment (unknown how to confirm from the sources).","plain_action":"","needs_analyst":false,"not_affected_if":["versions-outside-3.17.0-to-3.32.2","assertions-disabled","trusted-servers-only"],"who_is_affected":"Only clients built or configured with verbose WinPR assertions are reported to crash; the trigger is a malicious RDP server that a client connects to. Systems that only connect to trusted RDP servers are lower risk. Teams that embed FreeRDP in their own tools should check which version they ship.","user_interaction":"yes","needs_special_setup":"yes","severity_if_unknown":"high"},"cost_usd":0.00071,"input_tokens":4188,"output_tokens":582,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-121395':13A,16A '-2026':12A,15A '16':103C '3.17.0':68C '3.32.2':70C 'abort':46B,107C 'adjac':97C 'assert':30B,63B,73C,83C 'beyond':101C 'bit':104C 'client':7A,48B,109C 'coeffici':45B,99C 'contain':71C 'craft':38B,93C 'crash':6A 'cve':11A,14A 'decod':27B,79C 'denial':54B 'describ':52B 'differenti':26B,78C 'enabl':65B,85C 'fail':28B 'failur':74C 'freerdp':1A,17B,23B,66C 'linux':18B 'll3':98C 'malici':2A,33B,87C 'out-of-rang':41B 'packag':19B 'process':49B,110C 'rang':44B,105C 'rdp':3A,20B,34B,88C 'remotefx':9A,21B,25B,77C,94C 'send':36B,91C 'server':4A,35B,89C 'servic':56B 'sign':102C 'sourc':51B 'sum':100C 'tile':10A,39B,95C 'trigger':59B 'verbos':61B,81C 'via':8A 'window':22B 'winpr':62B,82C","nicknames":[],"mitigations":[],"who_affected":"Only clients built or configured with verbose WinPR assertions are reported to crash; the trigger is a malicious RDP server that a client connects to. Systems that only connect to trusted RDP servers are lower risk. Teams that embed FreeRDP in their own tools should check which version they ship.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["freerdp","high","linux","package","rdp","remotefx","windows"],"first_public_at":"2026-10-19T12:04:50+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-121395","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121395","severity":null,"published_at":"2026-11-03T15:17:27+00:00","modified_at":"2026-11-03T15:17:27+00:00","first_seen_at":"2026-11-03T15:21:57+00:00","fetched_at":"2026-11-03T15:21:57+00:00","note":null}],"documents":[{"id":58313,"url":"https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-cg4f-57hc-v7w7","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-10-19T12:04:50+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"},{"id":58314,"url":"https://www.vulncheck.com/advisories/freerdp-3.17.0-before-3.32.2-denial-of-service-via-remotefx-decoder","title":"Third-party advisory: www.vulncheck.com","kind":"advisory","source":"nvd","publisher":"research","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":"Third-party advisory: www.vulncheck.com"}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}