External risk intelligence

Linksys E1700 SSID1 MAC Filter Stack Buffer Overflow

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-108892

The vulnerability affects a network-facing management interface (MAC filtering) on a Linksys router. Such administrative web interfaces and router management endpoints are commonly accessible over the network, and while often intended for local access, they are frequently exposed or reachable in typical home and small office deployment patterns.

Memory Corruption

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 advisory details a critical vulnerability in Linksys E1700 network devices, specifically within the Mac Filter component. The issue, a stack-based buffer overflow, can be exploited remotely and has been publicly disclosed, increasing the risk of its utilization. Given the vendor's lack of response, confirming relevance and exposure is the primary concern.

Remote attackers can overflow router memory.
Critical for all internet-connected network devices.
Confirm exposure and investigate router security.

Attack Path

How an attacker could exploit the issue

An attacker can remotely exploit this vulnerability by sending specially crafted requests to the device's web interface. The vulnerable function, `ssid1MACFilter`, within the Mac Filter component is susceptible to manipulation. If successful, this could lead to a stack-based buffer overflow, potentially allowing for significant impact on the device.

Accessible over the network.
Triggered via the Mac Filter function.
High impact on device integrity and availability.

Live Threat

Current exploitation, exposure, and threat context

A stack-based buffer overflow in the MAC filter function of a Linksys router could allow remote attackers to affect the device's operation and potentially its network traffic. This could occur when an attacker crafts specific input to the `newap_text_%d` argument, leading to the overflow.

Router configuration and network access at risk.
Remotely triggered via crafted input.
Could disrupt network service availability.

Operational Fix

Recommended remediation, mitigation, and detection steps

Given this vulnerability affects a Linksys router's MAC filter functionality and is remotely exploitable, the primary responsibility likely lies with the network infrastructure team or the asset owner responsible for managing network devices. The first practical move is to identify all Linksys E1700 devices within the environment, determine their network exposure and business criticality, and then confirm the accountable owner to plan appropriate remediation.

Network infrastructure team owns remediation.
Verify device exposure and criticality.
Plan firmware update or isolation.

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 the Linksys E1700 device?

The Linksys E1700 is a wireless router designed for home and small office networks. It provides connectivity for devices to access the internet and includes administrative management features, such as MAC filtering, which allows users to control which specific hardware devices are permitted to connect to the network.

What does this stack-based buffer overflow mean for CVE-2026-108892?

This vulnerability, classified as CWE-119 and CWE-121, occurs when the router's software receives more data than its memory buffer can handle. By sending specifically crafted input to the MAC filter function, an attacker can overwrite adjacent memory, potentially causing the device to crash or allowing the execution of unauthorized commands.

How is this vulnerability triggered on my router?

The flaw is triggered by sending a malicious request to the /goform/ssid1MACFilter endpoint on the router's web interface. Specifically, manipulating the 'newap_text_%d' argument leads to the overflow. Normal, non-malicious interaction with the router's administrative settings does not trigger this error.

Is my Linksys E1700 at risk?

Halo Surface Signal indicates that because this vulnerability exists within a network-facing management interface, the risk is elevated. If your router's administrative web interface is accessible over the internet or reachable by untrusted parties on your local network, it is a primary concern for potential remote access.

What should I do if I use this Linksys device?

First, locate all E1700 devices in your environment and assess their exposure. Since the vendor has not responded to this issue, you should prioritize restricting access to the device's management interface to trusted internal networks only. Monitor for any vendor security updates, and consider isolating the device if it remains publicly accessible.

References

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.