---
id: "CVE-2026-121404"
kind: "vulnerability"
aliases: ["CVE-2026-121404"]
title: "FreeRDP: authenticated clients can exhaust server CPU via empty RDP messages"
severity: "high"
cvss: 7.1
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["freerdp", "linux", "rdp", "runtime", "self-hosted"]
not_affected_if: ["auth-required", "no-shadow-server", "rdp-not-exposed"]
published_at: "2026-11-03T15:17:28+00:00"
first_seen_at: "2026-11-03T15:21:58+00:00"
updated_at: "2026-11-03T15:23:02+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121404", "first_seen_at": "2026-11-03T15:21:58+00:00"}]
---

# FreeRDP: authenticated clients can exhaust server CPU via empty RDP messages

FreeRDP's shadow server, which lets remote desktop clients view and control a machine, can be made to spin server threads by an authenticated client sending zero-length drdynvc DATA messages. The attacker can consume full CPU cores until the client disconnects, causing denial of service.

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

## How to check

- Check the installed FreeRDP version with `xfreerdp --version` or your package manager, and compare it to the fixed version below.
- Confirm whether you run the FreeRDP shadow server (`freerdp-shadow-cli` or a shadow-based remote desktop service); unknown if the sources say how to detect it otherwise.

## Fix

- FreeRDP: move to `3.32.2` or later.

## Timeline

- 2026-11-03T15:21:58+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121404

## Documents

- [advisory] Vendor advisory: github.com https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-fqcj-rwww-2498
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/freerdp-before-3.32.2-shadow-server-cpu-exhaustion-via-zero-length-dvc-data

## From the sources

FreeRDP before 3.32.2 contains a denial of service vulnerability in the shadow server that allows authenticated RDP clients to spin server threads by sending zero-length drdynvc DATA PDUs. Attackers can send empty DATA messages on opened audin or rdpgfx channels, so that FreeRDP_WTSVirtualChannelRead never consumes them, consuming full CPU cores until disconnect.

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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_