{"id":"CVE-2026-121962","kind":"vulnerability","aliases":["CVE-2026-121962"],"related":[],"title":"FreeRDP: malicious server split reads overflow heap, crashing client","description":"FreeRDP before 3.32.2 contains a heap buffer overflow in transport_default_read_pdu when handling partial Early User Authorization reads during PROTOCOL_HYBRID_EX CredSSP. A malicious RDP server can split the four-byte EUA result into short reads that advance the stream pointer beyond the 16 KiB allocation, causing an out-of-bounds write and client denial of service.","summary":"FreeRDP clients mishandle a split four-byte Early User Authorization result during CredSSP hybrid-extended connections, writing past a 16 KiB heap buffer. A malicious RDP server can use this to crash the client, and an out-of-bounds write can enable more.","severity":"high","cvss":8.1,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["freerdp","linux","package","rdp-clients","windows"],"not_affected_if":["fixed-version","trusted-servers-only"],"how_to_check":"- Check the FreeRDP version in use, for example with `xfreerdp /version`.\n- Look for FreeRDP client builds or libraries bundled in other applications.","fix":"- FreeRDP: move to `3.32.2` or later.","status":"open","published_at":"2026-11-04T16:17:49+00:00","first_seen_at":"2026-11-04T16:28:14+00:00","triaged_at":"2026-11-04T16:28:50+00:00","updated_at":"2026-11-04T16:28:50+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-11-04T16:28:50Z","model":"claude-haiku-5-5","output":{"fix":"- FreeRDP: move to `3.32.2` or later.","reach":"network","title":"FreeRDP: malicious server split reads overflow heap, crashing client","impact":"medium","summary":"FreeRDP clients mishandle a split four-byte Early User Authorization result during CredSSP hybrid-extended connections, writing past a 16 KiB heap buffer. A malicious RDP server can use this to crash the client, and an out-of-bounds write can enable more.","audience":"developers","category":"package","nicknames":[],"who_cares":["freerdp","rdp-clients","linux","windows"],"confidence":0.7,"fix_status":"available","needs_auth":"no","worst_case":"client crashes; out-of-bounds write may allow more","analyst_note":"Confirm whether the out-of-bounds write is exploitable beyond denial of service; check the vendor advisory on github.com and the VulnCheck advisory.","how_to_check":"- Check the FreeRDP version in use, for example with `xfreerdp /version`.\n- Look for FreeRDP client builds or libraries bundled in other applications.","plain_action":"","needs_analyst":true,"not_affected_if":["fixed-version","trusted-servers-only"],"who_is_affected":"Anyone running a FreeRDP client before 3.32.2 that connects to RDP servers using PROTOCOL_HYBRID_EX CredSSP. The risk comes from connecting to a malicious or compromised RDP server, so clients that only connect to trusted servers are less exposed. Sources do not describe any server-side exposure.","user_interaction":"yes","needs_special_setup":"yes","severity_if_unknown":"high"},"cost_usd":0.00071,"input_tokens":4208,"output_tokens":579,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-121962':12A,15A '-2026':11A,14A '16':44B,115C '3.32.2':70C 'advanc':109C 'alloc':117C 'author':33B,86C 'beyond':113C 'bound':64B,123C 'buffer':47B,74C 'byte':30B,102C 'caus':118C 'client':9A,21B,24B,58B,126C 'connect':40B 'contain':71C 'crash':8A,56B 'credssp':36B,92C 'cve':10A,13A 'default':78C 'denial':127C 'earli':31B,84C 'enabl':67B 'eua':103C 'ex':91C 'extend':39B 'four':29B,101C 'four-byt':28B,100C 'freerdp':1A,16B,23B,68C 'handl':82C 'heap':7A,46B,73C 'hybrid':38B,90C 'hybrid-extend':37B 'kib':45B,116C 'linux':17B 'malici':2A,49B,94C 'mishandl':25B 'out-of-bound':61B,120C 'overflow':6A,75C 'packag':18B 'partial':83C 'past':42B 'pdu':80C 'pointer':112C 'protocol':89C 'rdp':20B,50B,95C 'rdp-client':19B 'read':5A,79C,87C,107C 'result':34B,104C 'server':3A,51B,96C 'servic':129C 'short':106C 'split':4A,27B,98C 'stream':111C 'transport':77C 'use':53B 'user':32B,85C 'window':22B 'write':41B,65B,124C","nicknames":[],"mitigations":[],"who_affected":"Anyone running a FreeRDP client before 3.32.2 that connects to RDP servers using PROTOCOL_HYBRID_EX CredSSP. The risk comes from connecting to a malicious or compromised RDP server, so clients that only connect to trusted servers are less exposed. Sources do not describe any server-side exposure.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["freerdp","high","linux","package","rdpclients","windows"],"campaign_type":null,"first_public_at":"2026-10-20T17:18:28+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/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-2026-121962","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121962","severity":null,"published_at":"2026-11-04T16:17:49+00:00","modified_at":"2026-11-04T16:17:49+00:00","first_seen_at":"2026-11-04T16:28:14+00:00","fetched_at":"2026-11-04T16:28:14+00:00","note":null}],"documents":[{"id":68497,"url":"https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-j536-qc58-pmf8","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-10-20T17:18:28+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"},{"id":68498,"url":"https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-early-user-authorization-read","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"}