CVE-2025-11293: Belkin F9K1015 Buffer Overflow Vulnerability

CVE-2025-11293 Overview

CVE-2025-11293 is a buffer overflow vulnerability in the Belkin F9K1015 wireless router running firmware version 1.00.10. The flaw resides in the /goform/formConnectionSetting endpoint, where the max_Conn parameter is processed without proper bounds checking [CWE-119]. Remote attackers with low privileges can trigger memory corruption over the network to compromise device confidentiality, integrity, and availability. The exploit has been publicly disclosed, and the vendor did not respond to coordinated disclosure attempts.

Critical Impact

Remote attackers can corrupt router memory through a crafted HTTP request to /goform/formConnectionSetting, potentially leading to arbitrary code execution on the device.

Affected Products

• Belkin F9K1015 router (hardware)
• Belkin F9K1015 firmware version 1.00.10
• Deployments exposing the web management interface to untrusted networks

Discovery Timeline

• 2025-10-05 - CVE-2025-11293 published to NVD
• 2025-10-07 - Last updated in NVD database

Technical Details for CVE-2025-11293

Vulnerability Analysis

The vulnerability exists in the HTTP handler that processes connection configuration requests on the Belkin F9K1015 router. When a client submits a POST request to /goform/formConnectionSetting, the firmware parses the max_Conn argument and copies its value into a fixed-size buffer without validating input length. Supplying an oversized value overflows the buffer and corrupts adjacent memory in the embedded web server process.

Because the affected handler runs with elevated privileges on the device, successful exploitation can lead to control-flow hijacking, daemon crashes, or persistent compromise of the router. The advisory notes that Belkin was contacted prior to disclosure but provided no response, leaving the device without an official patch.

Root Cause

The root cause is improper restriction of operations within the bounds of a memory buffer [CWE-119]. The formConnectionSetting handler trusts the length and content of the max_Conn parameter supplied by the HTTP client. No length validation, sanitization, or safe string-copy routine is applied before the value is written into the destination buffer.

Attack Vector

An authenticated attacker with low-privilege access to the router's web interface can send a crafted HTTP POST request to /goform/formConnectionSetting with an oversized max_Conn value. The attack is network-reachable and requires no user interaction. Public proof-of-concept material is referenced in the GitHub PoC Documentation and tracked in VulDB #327174.

Detection Methods for CVE-2025-11293

Indicators of Compromise

• HTTP POST requests to /goform/formConnectionSetting containing abnormally long max_Conn values
• Unexpected reboots, web interface crashes, or httpd restarts on the F9K1015
• Outbound connections from the router to unknown hosts following administrative HTTP traffic
• Configuration changes to firewall, DNS, or routing tables that were not initiated by an administrator

Detection Strategies

• Inspect HTTP request bodies at the network perimeter for max_Conn parameter lengths exceeding expected numeric ranges
• Alert on repeated authentication or POST activity targeting /goform/* endpoints from a single source
• Correlate router syslog crash events with preceding HTTP administrative requests

Monitoring Recommendations

• Forward router syslog and authentication events to a centralized log platform for retention and correlation
• Baseline normal management traffic patterns and alert on deviations targeting the web administration interface
• Monitor DNS and routing configuration on downstream clients to detect router-level tampering

How to Mitigate CVE-2025-11293

Immediate Actions Required

• Restrict access to the router web management interface to trusted management VLANs or IP ranges only
• Disable remote (WAN-side) administration on all F9K1015 devices
• Rotate administrative credentials and enforce strong, unique passwords to limit low-privilege attacker access
• Inventory affected devices and plan replacement, as the F9K1015 is an end-of-life consumer router

Patch Information

No vendor patch is available. The CVE record states that Belkin was contacted prior to public disclosure but did not respond. Administrators should treat the device as unpatched and consider replacement with a currently supported router platform. Refer to VulDB #327174 (CTIID) for ongoing tracking.

Workarounds

• Place the router behind an upstream firewall that filters inbound HTTP traffic to the management interface
• Segment the router from sensitive internal networks and IoT endpoints to limit lateral movement
• Replace the F9K1015 with a supported model that receives security updates from the vendor

# Example: block external access to the router admin interface using iptables
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP