---
id: "CVE-2026-111880"
kind: "vulnerability"
aliases: ["CVE-2026-111880"]
title: "FreeRDP: crafted NTLM message writes past heap buffer, unauthenticated"
severity: "high"
cvss: 8.3
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["freerdp", "package", "rdp-server", "self-hosted", "windows-remote-access"]
not_affected_if: ["client-only", "no-rdp-server"]
published_at: "2026-10-17T19:16:28+00:00"
first_seen_at: "2026-10-23T21:57:14+00:00"
updated_at: "2026-10-25T03:02:32+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111880", "first_seen_at": "2026-10-23T21:57:14+00:00"}]
---

# FreeRDP: crafted NTLM message writes past heap buffer, unauthenticated

FreeRDP's server-side NTLM hash-callback path does not validate the MIC offset in AUTHENTICATE_MESSAGE, so a crafted message makes it write 16 zero bytes past an allocation. An unauthenticated attacker who can reach the RDP server can trigger this heap out-of-bounds write.

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

## How to check

- Run `xfreerdp /version` or check the installed FreeRDP package version on hosts running a FreeRDP server
- Check whether the server build is at or above `3.32.0`; versions from `2.0.0` up to but not including `3.32.0` are affected

## Fix

- Upgrade FreeRDP to `3.32.0` or later
- Until patched, restrict network access to the RDP server port to trusted hosts

## Timeline

- 2026-10-23T21:57:14+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-111880

## From the sources

FreeRDP versions from 2.0.0 before 3.32.0 contain a heap out-of-bounds write in the server hash-callback NTLM path that fails to validate the MIC offset. Unauthenticated attackers can send a crafted AUTHENTICATE_MESSAGE with a backward session-key offset and MIC offset to write 16 zero bytes beyond the allocation.

---

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