External risk intelligence

M3WebServer API Key Hardcoding Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-49191

The vulnerability affects web server firmware in a router/gateway device. Such products are typically deployed as internet-facing network appliances, making their web interfaces and associated services commonly accessible from the public internet.

Authentication Bypass

Acer Connect M6e 5g Firmware

m6e_ai_1.00.000019 and earlier

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This critical vulnerability involves hard-coded API keys in the M3WebServer production build, which can be exposed through error pages. This could allow unauthorized access to backend systems, potentially impacting sensitive data and operations. Given the external exposure of affected devices, confirming relevance and exposure is the primary concern.

API keys are exposed by the web server.
Critical exposure; affects internet-facing devices.
Confirm relevance and exposure across your estate.

Attack Path

How an attacker could exploit the issue

An attacker can reach a critical vulnerability in the M3WebServer by exploiting verbose error messages. These messages reveal hard-coded backend API keys, which can then be used to access sensitive data and operations.

Publicly accessible web interface required.
Triggered by viewing error handling pages.
Leads to sensitive data exposure and control.

Live Threat

Current exploitation, exposure, and threat context

The production build of M3WebServer hard-codes backend API keys, which attackers could intercept when error handling pages are verbose. This could expose sensitive information or allow unauthorized access to backend services.

Sensitive API keys could be exposed.
Verbose error messages may reveal keys.
Unauthorized access to backend services.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the M3WebServer, which hard-codes API keys and exposes them via error handling, likely requires coordinated action between the platform team managing the web server deployment and the application owners responsible for the backend services. The first practical step is to identify all instances of the affected M3WebServer, determine their exposure and business criticality, and then confirm the accountable owner before planning remediation.

Platform and application owners should collaborate.
Verify all M3WebServer deployments and exposure.
Plan targeted remediation based on identified risk.

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.

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Frequently asked questions

What is M3WebServer and what is it used for?

M3WebServer is the web server component integrated into the firmware of Acer Connect M6E 5G router and gateway devices. It powers the management interface and handles communication between the hardware and backend services, essentially acting as the bridge that allows users and systems to interact with the device's networking features.

How does CVE-2026-49191 work?

This vulnerability, classified as Improper Authentication (CWE-287), occurs because the software includes sensitive backend API keys directly within the production code. When the server encounters an issue and generates a verbose error page, it inadvertently displays these hard-coded keys to the viewer, allowing unauthorized parties to potentially impersonate the system.

What triggers the vulnerability in M3WebServer?

The vulnerability is triggered when a user or attacker causes the web server to generate an error response. By navigating to paths or sending requests that force the system to display detailed error handling pages, the sensitive API keys are leaked. Simply accessing the standard, functional parts of the web interface without triggering an error condition does not expose the keys.

Why is this CVE considered relevant for my network?

According to Halo Surface Signal, this vulnerability is highly relevant because it affects web server firmware in network appliances like routers, which are frequently deployed as internet-facing devices. If your affected M3WebServer interface is accessible from the public internet, it can be reached and exploited by external parties without requiring prior access to your internal network.

How should I respond if I am running this technology?

Begin by identifying all devices in your environment running the affected M3WebServer firmware versions. Coordinate with your platform and application teams to verify the specific exposure level of each deployment. Once identified, prioritize these systems for remediation, ensuring you have a clear understanding of the business criticality for each device before planning your update strategy.

References

community.acer.com/en/kb/articles/19707

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.