CVE-2026-42961: ELECOM Wireless LAN CSRF Vulnerability

CVE-2026-42961 Overview

CVE-2026-42961 is a Cross-Site Request Forgery (CSRF) vulnerability affecting ELECOM wireless LAN access point devices. The devices implement a CSRF protection mechanism, but the handling of CSRF tokens is inadequate. An authenticated user who views a malicious page while logged in to the device management interface may be tricked into performing unintended operations on the access point.

The issue is tracked as [CWE-344] Use of Invariant Value in Dynamically Changing Context. The vulnerability requires user interaction and originates from a network-adjacent web context.

Critical Impact

Attackers can coerce authenticated administrators into executing unintended state-changing operations on ELECOM wireless LAN access points through crafted web content.

Affected Products

• ELECOM wireless LAN access point devices (specific models listed in vendor advisory)
• Refer to the Elecom Security News Update for the full list of affected firmware versions
• See JVN #03037325 for coordinated disclosure details

Discovery Timeline

• 2026-05-13 - CVE-2026-42961 published to NVD
• 2026-05-13 - Last updated in NVD database

Technical Details for CVE-2026-42961

Vulnerability Analysis

The vulnerability stems from inadequate validation of CSRF tokens in the web management interface of ELECOM wireless LAN access points. While a CSRF protection mechanism exists, its implementation does not properly bind tokens to user sessions or validate token freshness on each request. This weakness aligns with [CWE-344], where a value expected to vary across contexts remains invariant.

An attacker who crafts a malicious web page can include hidden requests targeting the access point's administrative endpoints. If a logged-in administrator visits the page in the same browser session, the browser submits the forged requests with valid authentication cookies. The flawed token check fails to distinguish legitimate user-initiated requests from attacker-supplied ones.

Root Cause

The root cause is improper handling of anti-CSRF tokens. Tokens may be static, predictable, or not validated server-side against the authenticated session. As a result, the protection mechanism provides no meaningful guarantee that incoming state-changing requests originated from the intended user interface.

Attack Vector

The attack vector is network-based with required user interaction. The attacker hosts or injects malicious HTML or JavaScript that issues HTTP requests to the access point's management interface. The victim must be authenticated to the device's web console when visiting the attacker-controlled page. Successful exploitation may modify device configuration, such as wireless settings, credentials, or routing parameters, without the administrator's knowledge.

No verified public exploitation code is available. Refer to the JVN advisory for technical disclosure details.

Detection Methods for CVE-2026-42961

Indicators of Compromise

• Unexpected configuration changes on ELECOM access points, including modified Wi-Fi credentials, SSID values, or administrative passwords
• HTTP requests to the device management interface containing Referer headers pointing to untrusted external origins
• Administrative actions logged outside of normal maintenance windows or from unexpected client IP addresses

Detection Strategies

• Inspect web proxy and firewall logs for outbound user traffic followed by inbound POST requests to access point management URLs from the same client
• Correlate administrator browser activity with device configuration change events to identify cross-origin triggers
• Monitor for HTML forms or JavaScript on visited sites that submit requests to internal RFC 1918 addresses hosting management interfaces

Monitoring Recommendations

• Enable and centralize device audit logs from ELECOM access points where supported by firmware
• Alert on configuration changes that occur without a corresponding administrator authentication event from a trusted source
• Track DNS and HTTP telemetry for connections to known malicious sites from hosts that also administer network infrastructure

How to Mitigate CVE-2026-42961

Immediate Actions Required

• Apply firmware updates published by ELECOM as referenced in the Elecom Security News Update
• Log out of the device management interface immediately after completing administrative tasks to invalidate session cookies
• Restrict access to the access point's management interface to a dedicated management VLAN or trusted IP range

Patch Information

ELECOM has published security guidance and firmware information at the vendor advisory. Coordinated disclosure details are available through JVN #03037325. Administrators should identify their device model and apply the corresponding firmware version listed by the vendor.

Workarounds

• Use a dedicated browser or browser profile for device administration, with no other tabs open during configuration sessions
• Disable remote management interfaces on the WAN side of the access point if not strictly required
• Change default administrator credentials and enforce strong, unique passwords to reduce post-CSRF impact
• Place access point management interfaces behind a network segmentation boundary that blocks browser-originated traffic from user workstations