Multiple Linksys range extenders are vulnerable to a stack-based buffer overflow that could allow remote code execution by an authenticated attacker.

The vulnerability exists in the DisablePasswordAlertRedirect function of the /goform/DisablePasswordAlertRedirect endpoint. An authenticated attacker can supply an overly long string to the hint parameter, which is copied to a local stack variable without bounds checking, resulting in a buffer overflow that can be leveraged to overwrite the function return address.

The ability to execute arbitrary code on network infrastructure poses a significant risk to organizational security. Successful exploitation could lead to full device compromise, unauthorized access to internal network traffic, and potential persistence within the environment. Given the CVSS score of 8.8, this flaw represents a high-severity risk that requires immediate attention to prevent lateral movement or interception of sensitive data.

Immediate Action: Since no official patch is currently available, restrict access to the web management interface of the affected devices to trusted IP addresses only and disable remote management features.

Proactive Monitoring: Monitor network traffic and device logs for irregular POST requests directed at the /goform/DisablePasswordAlertRedirect endpoint or unexpected device reboots.

Compensating Controls: Deploy a Web Application Firewall (WAF) or an Intrusion Prevention System (IPS) rule to inspect and block excessively long input strings within the hint parameter of HTTP requests.

Public Exploit Available: Yes, a published proof-of-concept exists in the technical write-up provided by the researcher (Jiaqian Peng).

Given the availability of a public proof-of-concept and the critical nature of buffer overflow vulnerabilities, this issue should be treated with high priority. Administrators must harden the management interface access immediately and maintain vigilance for vendor-provided firmware updates. Failure to mitigate this risk leaves critical network infrastructure exposed to potential remote takeover.