A critical stack-based buffer overflow vulnerability in multiple Linksys range extenders allows remote authenticated attackers to compromise device integrity and availability.

The vulnerability is a stack-based buffer overflow located in the inboundFilterAdd function within the /goform/inboundFilterAdd endpoint. Attackers with low privileges can trigger this overflow by sending a maliciously crafted ruleName parameter, which lacks proper input length validation, leading to memory corruption and potential code execution.

The exploitation of this vulnerability can lead to a complete denial of service for the affected network infrastructure, causing significant operational downtime. Furthermore, the potential for arbitrary code execution poses a severe risk of unauthorized access to the local network or sensitive configuration data, threatening the overall security posture of the environment. The CVSS score of 8.8 reflects the high severity of this flaw, particularly given the ability to achieve full system impact.

Immediate Action: Since no official vendor patch is currently available, administrators should restrict access to the management interface of the affected devices to trusted internal IP addresses only.

Proactive Monitoring: Monitor device logs for unusual POST requests directed at /goform/inboundFilterAdd, particularly those containing excessively long strings in the ruleName parameter.

Compensating Controls: Implement a Web Application Firewall or network access control list to filter and block traffic containing oversized input parameters directed at the range extender management console.

Public Exploit Available: Yes, a proof-of-concept is available via the researcher's published technical write-up on GitHub.

Given the lack of a vendor-supplied patch and the availability of a public proof-of-concept, users must treat this vulnerability as a high-priority risk. Immediately isolate the management interfaces of these devices from untrusted networks and prepare to apply firmware updates as soon as Linksys releases a security patch.