---
id: CVE-2026-93866
title: >-
  Fireware OS Pre-Authentication Integer Overflow in Access Portal Allows
  Out-of-Bounds Write
summary: >-
  An integer overflow vulnerability in the WebSocket connection handling used by
  WatchGuard Fireware OS's Access Portal allows a remote, unauthenticated
  attacker to write beyond the bounds of a heap buffer by sending a specially
  crafted re…
severity: critical
cvss: 9.2
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'
cvssSource: cna
cwe:
  - CWE-190
  - CWE-288
  - CWE-787
vendor: WatchGuard
product: Fireware OS
affected:
  - fireware_os >= 2025.1 < 2026.4
  - fireware_os >= 12.0 < 12.12.4
  - fireware_os >= 12.0 < 12.5.22
published: '2026-10-27'
updated: '2026-10-27'
sourceUpdated: '2026-10-27T15:52:27.871Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-93866'
references:
  - url: 'https://psirt.watchguard.com/CVE-2026-93866'
tags:
  - cve.org
ingestedAt: '2026-10-27T16:11:59.475Z'
---

## Overview

An integer overflow vulnerability in the WebSocket connection handling used by WatchGuard Fireware OS's Access Portal allows a remote, unauthenticated attacker to write beyond the bounds of a heap buffer by sending a specially crafted request while the Access Portal feature is enabled.

## Affected

- `fireware_os >= 2025.1 < 2026.4`
- `fireware_os >= 12.0 < 12.12.4`
- `fireware_os >= 12.0 < 12.5.22`

## Remediation

Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22