{"id":"CVE-2026-121396","kind":"vulnerability","aliases":["CVE-2026-121396"],"related":[],"title":"FreeRDP client: malformed RD Gateway packet aborts the connecting client process","description":"FreeRDP clients from 3.0.0 before 3.32.2 built with verbose WinPR assertions contain a reachable assertion in rts_read_auth_verifier triggered by malformed RTS padding. Attackers controlling an RD Gateway can send a crafted RPC-over-HTTP RTS PDU with inconsistent authentication padding to abort the connecting client process.","summary":"FreeRDP clients from 3.0.0 before 3.32.2, built with verbose WinPR assertions, crash when a connected RD Gateway sends a crafted RPC-over-HTTP packet with inconsistent authentication padding. An attacker controlling the gateway can abort the client process, which is a denial of service rather than code execution.","severity":"medium","cvss":5.3,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["freerdp","package","rd-gateway","remote-desktop"],"not_affected_if":["direct-rdp-only","non-verbose-build","other-rdp-client"],"how_to_check":"- Check the FreeRDP client version with `xfreerdp /version` or the installed package version, and look for anything below `3.32.2`.\n- Check whether the build enables verbose WinPR assertions; the sources do not say how to detect this.","fix":"- FreeRDP clients: move to `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":"2026-11-03T15:24:33+00:00","updated_at":"2026-11-03T15:24:33+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-11-03T15:24:33Z","model":"claude-haiku-5-5","output":{"fix":"- FreeRDP clients: move to `3.32.2` or later.","reach":"network","title":"FreeRDP client: malformed RD Gateway packet aborts the connecting client process","impact":"low","summary":"FreeRDP clients from 3.0.0 before 3.32.2, built with verbose WinPR assertions, crash when a connected RD Gateway sends a crafted RPC-over-HTTP packet with inconsistent authentication padding. An attacker controlling the gateway can abort the client process, which is a denial of service rather than code execution.","audience":"businesses","category":"package","nicknames":[],"who_cares":["freerdp","rd-gateway","remote-desktop"],"confidence":0.7,"fix_status":"available","needs_auth":"unknown","worst_case":"Client process is aborted, causing denial of service only","analyst_note":"","how_to_check":"- Check the FreeRDP client version with `xfreerdp /version` or the installed package version, and look for anything below `3.32.2`.\n- Check whether the build enables verbose WinPR assertions; the sources do not say how to detect this.","plain_action":"","needs_analyst":false,"not_affected_if":["direct-rdp-only","non-verbose-build","other-rdp-client"],"who_is_affected":"Teams that connect to Windows machines through an RD Gateway with FreeRDP clients from 3.0.0 up to 3.32.2 built with verbose WinPR assertions. The exposure comes from a gateway the client trusts, so clients that connect only directly to hosts, or use other RDP clients, are not affected by this flaw.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000714,"input_tokens":4201,"output_tokens":587,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-121396':14A,17A '-2026':13A,16A '3.0.0':29B,78C '3.32.2':31B,80C 'abort':7A,61B,120C 'assert':36B,85C,89C 'attack':56B,100C 'auth':93C 'authent':53B,117C 'built':32B,81C 'client':2A,10A,27B,63B,76C,123C 'code':73B 'connect':9A,40B,122C 'contain':86C 'control':57B,101C 'craft':45B,108C 'crash':37B 'cve':12A,15A 'denial':68B 'desktop':25B 'execut':74B 'freerdp':1A,18B,26B,75C 'gateway':5A,22B,42B,59B,104C 'http':49B,112C 'inconsist':52B,116C 'malform':3A,97C 'packag':19B 'packet':6A,50B 'pad':54B,99C,118C 'pdu':114C 'process':11A,64B,124C 'rather':71B 'rd':4A,21B,41B,103C 'rd-gateway':20B 'reachabl':88C 'read':92C 'remot':24B 'remote-desktop':23B 'rpc':47B,110C 'rpc-over-http':46B,109C 'rts':91C,98C,113C 'send':43B,106C 'servic':70B 'trigger':95C 'verbos':34B,83C 'verifi':94C 'winpr':35B,84C","nicknames":[],"mitigations":[],"who_affected":"Teams that connect to Windows machines through an RD Gateway with FreeRDP clients from 3.0.0 up to 3.32.2 built with verbose WinPR assertions. The exposure comes from a gateway the client trusts, so clients that connect only directly to hosts, or use other RDP clients, are not affected by this flaw.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["freerdp","medium","package","rdgateway","remotedesktop"],"first_public_at":"2026-10-19T12:35:36+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/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-2026-121396","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121396","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":58315,"url":"https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6p3w-fv52-cf24","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-10-19T12:35:36+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"},{"id":58316,"url":"https://www.vulncheck.com/advisories/freerdp-3.0.0-before-3.32.2-denial-of-service-via-rts-padding-assertion","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"}