External risk intelligence

Fireware OS Authentication Heap Buffer Overflow

CVE advisorySeverity: CRITICAL (CVSS 9.2)

CVE-2026-112710

The vulnerability exists in the authentication service's communication with a backend Active Directory server. This interaction typically occurs over internal networks between an appliance and a domain controller, rather than directly exposing the service to the public internet.

Buffer Overflow

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in the Fireware OS authentication service could allow an attacker to disrupt service or potentially execute arbitrary code by sending a specially crafted response to a configured Active Directory server. The primary concern at this time is to confirm whether this specific functionality is in use within our environment.

Authentication service vulnerability impacts Fireware OS.
Understand exposure: Active Directory communication is key.
Confirm relevance and assess any potential exposure.

Attack Path

How an attacker could exploit the issue

An attacker who can intercept or control traffic to a configured Active Directory server could trigger this vulnerability. By sending a specially crafted response, they could cause a buffer overflow in the Fireware OS authentication service, potentially leading to a denial of service or arbitrary code execution.

Network traffic interception is required.
Specially crafted server responses trigger it.
Risk of denial of service or code execution.

Live Threat

Current exploitation, exposure, and threat context

A heap-based buffer overflow in the Fireware OS authentication service could allow an attacker to cause a denial of service or potentially execute arbitrary code. This could occur when an attacker controls or intercepts traffic to the configured Active Directory server and sends a specially crafted response.

Authentication service data.
Crafted Active Directory responses.
Denial of service or code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Fireware OS authentication service's vulnerability to heap-based buffer overflow, triggered by a crafted response from an Active Directory server, requires a coordinated response. Infrastructure and security teams are likely responsible for identifying and securing the Active Directory integration points, while system owners must confirm the business criticality and reachability of affected services. The first practical step is to inventory all Fireware OS instances, verify their AD configurations, and assess exposure to determine the highest priority for remediation.

Identify accountable Fireware OS and AD owners.
Verify AD server communication and business criticality.
Plan remediation based on exposure and impact.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is Fireware OS and where is it used?

Fireware OS is the underlying operating system powering WatchGuard network security appliances. It provides core functionality such as firewalling, VPN management, and user authentication. Organizations use it to secure their network perimeters and manage secure access for employees and systems.

What does heap-based buffer overflow mean for CVE-2026-112710?

This is a memory corruption weakness, specifically CWE-122. It happens when the software attempts to store more data in a reserved memory area (the heap) than it can hold. In this case, an attacker sends malformed data that overwrites adjacent memory, potentially causing the service to crash or allowing the execution of unauthorized commands.

How is this vulnerability triggered by an attacker?

The flaw is triggered only if an attacker can intercept or control the network traffic between the Fireware OS appliance and its configured Active Directory server. If the appliance is not actively communicating with an external or untrusted directory service, or if the traffic cannot be manipulated, the vulnerability remains untriggered.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal labels this as unlikely to be exposed. Because the vulnerability requires an attacker to intercept traffic between the appliance and an Active Directory server, it generally impacts internal network segments rather than being directly reachable from the public internet.

What are the first steps to address this CVE?

Start by identifying all deployed Fireware OS instances and checking if they are configured to authenticate via an Active Directory server. Once identified, verify these communication paths for security, prioritize instances that interact with untrusted networks, and await official guidance or security updates from the vendor.

References

psirt.watchguard.com/CVE-2026-112710

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.