---
id: CVE-2026-91953
title: >-
  FreeRDP versions before 3.31.0 contain a heap buffer overflow vulnerability in
  nego_send_negotiation_request() that fails to validate the
  LB_LOAD_BALANCE_INFO field length before writing to a fixed 512-byte buffer
summary: >-
  FreeRDP versions before 3.31.0 contain a heap buffer overflow vulnerability in
  nego_send_negotiation_request() that fails to validate the
  LB_LOAD_BALANCE_INFO field length before writing to a fixed 512-byte buffer. A
  malicious RDP server…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'
cwe:
  - CWE-120
vendor: freerdp
product: freerdp
affected:
  - freerdp < 3.31.0
patched:
  - freerdp 3.31.0
published: '2026-09-15'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T12:16:27.010'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-91953'
references:
  - url: 'https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-r9pv-ffph-6gg6'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/freerdp-before-3.31.0-heap-buffer-overflow-via-lb-load-balance-info
    label: disclosure@vulncheck.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-91953.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-91953'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2533959'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-91953'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-91953'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
epss: 0.00458
epssPercentile: 0.37076
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-15T16:01:12.250084Z'
ingestedAt: '2026-09-15T15:39:12.919Z'
---

## Overview

FreeRDP versions before 3.31.0 contain a heap buffer overflow vulnerability in nego_send_negotiation_request() that fails to validate the LB_LOAD_BALANCE_INFO field length before writing to a fixed 512-byte buffer. A malicious RDP server or man-in-the-middle can send a Server Redirection PDU with an oversized LB_LOAD_BALANCE_INFO value to overflow the buffer with attacker-controlled content, causing denial of service or heap corruption before authentication completes.

## Affected

- `freerdp < 3.31.0`

## Remediation

Upgrade past the affected range:

- `freerdp 3.31.0`

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-91953.json)