---
id: "CVE-2026-121962"
kind: "vulnerability"
aliases: ["CVE-2026-121962"]
title: "FreeRDP: malicious server split reads overflow heap, crashing client"
severity: "high"
cvss: 8.1
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["freerdp", "linux", "package", "rdp-clients", "windows"]
not_affected_if: ["fixed-version", "trusted-servers-only"]
published_at: "2026-11-04T16:17:49+00:00"
first_seen_at: "2026-11-04T16:28:14+00:00"
updated_at: "2026-11-04T16:28:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121962", "first_seen_at": "2026-11-04T16:28:14+00:00"}]
---

# FreeRDP: malicious server split reads overflow heap, crashing client

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.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the FreeRDP version in use, for example with `xfreerdp /version`.
- Look for FreeRDP client builds or libraries bundled in other applications.

## Fix

- FreeRDP: move to `3.32.2` or later.

## Timeline

- 2026-11-04T16:28:14+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121962

## Documents

- [advisory] Vendor advisory: github.com https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-j536-qc58-pmf8
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/freerdp-before-3.32.2-heap-buffer-overflow-via-early-user-authorization-read

## From the sources

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.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_