CVE-2026-4544 Overview
CVE-2026-4544 is a cross-site scripting (XSS) vulnerability [CWE-79] affecting the Wavlink WL-WN578W2 wireless router running firmware version 221110. The flaw resides in an unspecified function within the /cgi-bin/login.cgi endpoint, which acts as the POST request handler for authentication. Attackers can manipulate the homepage, hostname, or login_page arguments to inject and execute arbitrary script content in the context of the web interface. The exploit details have been publicly disclosed, and the vendor did not respond to coordinated disclosure attempts.
Critical Impact
Remote attackers can inject malicious JavaScript into the router administration interface, enabling session theft, credential capture, or unauthorized device configuration changes against authenticated users.
Affected Products
- Wavlink WL-WN578W2 hardware device
- Wavlink WL-WN578W2 firmware version 221110
- Deployments exposing the /cgi-bin/login.cgi POST handler
Discovery Timeline
- 2026-03-22 - CVE-2026-4544 published to NVD
- 2026-04-30 - Last updated in NVD database
Technical Details for CVE-2026-4544
Vulnerability Analysis
The vulnerability stems from improper neutralization of user-supplied input in the login CGI handler of the Wavlink WL-WN578W2 router. The /cgi-bin/login.cgi script accepts POST parameters named homepage, hostname, and login_page without sanitizing or encoding the values before reflecting them in HTML responses. An attacker can craft a POST request containing script payloads in these parameters. When the response is rendered in a browser, the injected script executes within the origin of the router web interface.
This is a reflected XSS condition that requires user interaction. The attacker must lure an authenticated administrator or trick a user into submitting the malicious request. Successful execution can lead to administrative session hijacking, manipulation of router configuration, or pivoting to internal network resources.
Root Cause
The root cause is missing output encoding and input validation in the POST request handler logic for the login endpoint. User-controlled parameter values are placed directly into HTML output without contextual escaping, violating safe templating practices required to prevent script injection.
Attack Vector
Exploitation is performed remotely over the network against the router's HTTP management interface. The attacker delivers a malicious link or hosted page that triggers a POST request to /cgi-bin/login.cgi with weaponized values in homepage, hostname, or login_page. User interaction is required, and the privilege level required to reach the affected functionality is high, which limits practical exploitation.
No verified proof-of-concept code is provided. Public technical references include the GitHub Vulnerability Report WL-WN578W2 #6, the GitHub Vulnerability Report WL-WN578W2 #7, and the VulDB entry #352361.
Detection Methods for CVE-2026-4544
Indicators of Compromise
- POST requests to /cgi-bin/login.cgi containing HTML or JavaScript syntax such as <script>, onerror=, or javascript: in the homepage, hostname, or login_page parameters.
- Unexpected outbound connections from administrator browsers to attacker-controlled domains shortly after accessing the router management interface.
- Router configuration changes that do not correlate with legitimate administrator activity.
Detection Strategies
- Inspect HTTP proxy or network sensor logs for POST bodies targeting /cgi-bin/login.cgi with reflected payload patterns matching the three vulnerable parameters.
- Deploy web content inspection rules that flag HTML control characters (<, >, ", ') inside parameters expected to hold simple URL or hostname strings.
- Correlate browser-side script execution telemetry with sessions that recently authenticated to the Wavlink web interface.
Monitoring Recommendations
- Restrict and log all access to router administrative interfaces from corporate endpoints.
- Monitor for repeated login or configuration POST requests originating from unusual referrers or off-network sources.
- Alert on administrator workstations loading external scripts immediately after visiting an internal router IP address.
How to Mitigate CVE-2026-4544
Immediate Actions Required
- Remove the WL-WN578W2 management interface from any untrusted network and disable WAN-side administrative access.
- Require administrators to use a dedicated browser profile when accessing the router and to clear sessions immediately after use.
- Block inbound and outbound HTTP requests to /cgi-bin/login.cgi from unauthorized sources at the network perimeter.
Patch Information
No vendor patch is available. According to the disclosure, Wavlink was contacted early about this vulnerability but did not respond. Operators should assume the firmware version 221110 will remain unpatched and plan compensating controls or device replacement accordingly.
Workarounds
- Place the router management interface behind a VPN or segmented management VLAN reachable only by authorized administrators.
- Enforce browser-level script blocking or strict Content Security Policy via a reverse proxy when the router interface must remain accessible.
- Educate administrators to avoid clicking external links while authenticated to the router and to log out of the web interface after each session.
- Evaluate replacing the WL-WN578W2 with a vendor-supported device that receives security updates.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
