CVE-2025-5737: Totolink X15 Buffer Overflow Vulnerability

CVE-2025-5737 Overview

CVE-2025-5737 is a buffer overflow vulnerability in the TOTOLINK X15 router running firmware version 1.0.0-B20230714.1105. The flaw resides in the HTTP POST request handler at the endpoint /boafrm/formDosCfg, where the submit-url argument is processed without proper bounds checking. Remote attackers with low-privilege access can trigger memory corruption by sending a crafted request. Public disclosure of the exploit details has occurred, increasing the likelihood of opportunistic attacks against exposed devices. The weakness is classified under CWE-119, Improper Restriction of Operations within the Bounds of a Memory Buffer.

Critical Impact
Successful exploitation can corrupt router memory, leading to denial of service or arbitrary code execution on the embedded device.

Affected Products

TOTOLINK X15 hardware device
TOTOLINK X15 firmware version 1.0.0-B20230714.1105
Deployments exposing the device web management interface to untrusted networks

Discovery Timeline

2025-06-06 - CVE-2025-5737 published to NVD
2025-06-17 - Last updated in NVD database

Technical Details for CVE-2025-5737

Vulnerability Analysis

The TOTOLINK X15 web management daemon exposes the /boafrm/formDosCfg endpoint, which processes HTTP POST requests related to denial-of-service protection configuration. The handler reads the submit-url parameter from the incoming request body and copies it into a fixed-size stack or heap buffer without validating its length. When an attacker supplies an oversized value, the copy operation writes past the buffer boundary, overwriting adjacent memory. This memory corruption can crash the boa HTTP service or, depending on the layout, overwrite control-flow data such as saved return addresses or function pointers.

The attack reaches the device over the network with low complexity. The vulnerability requires low privileges, meaning an attacker must possess at least a valid session on the router's management interface. The exploit code has been disclosed publicly through a GitHub proof-of-concept and a VulDB entry, reducing the skill barrier for adversaries.

Root Cause

The root cause is the absence of length validation on user-controlled HTTP POST input before it is copied into a fixed-size memory region. The handler trusts the size of attacker-supplied data, a classic [CWE-119] memory safety failure common in embedded boa-based web stacks.

Attack Vector

An attacker sends a crafted HTTP POST request to /boafrm/formDosCfg containing an overlong submit-url parameter. If the device's management interface is reachable from the WAN or from a compromised LAN host, the request triggers the overflow. The result is service disruption or potential arbitrary code execution within the privileges of the router's web server process.

No verified exploitation code is reproduced here. Refer to the public proof-of-concept resource for technical details published by the original reporter.

Detection Methods for CVE-2025-5737

Indicators of Compromise

HTTP POST requests targeting /boafrm/formDosCfg with abnormally long submit-url parameter values
Unexpected crashes or restarts of the boa web server process on the TOTOLINK X15
Unusual outbound connections originating from the router following inbound management traffic
Configuration changes on the device that do not correspond to legitimate administrative activity

Detection Strategies

Inspect web server and reverse-proxy logs for POST requests to /boafrm/formDosCfg with parameter lengths exceeding typical values
Deploy network IDS signatures that flag oversized form fields in HTTP traffic destined for router management ports
Correlate authentication events on the router with subsequent crashes to identify post-authentication exploitation attempts

Monitoring Recommendations

Forward router syslog output to a central log repository and alert on boa process termination events
Monitor for unauthorized changes to firewall, DoS configuration, or DNS settings on the TOTOLINK X15
Track management interface access from non-administrative source addresses

How to Mitigate CVE-2025-5737

Immediate Actions Required

Restrict access to the router's web management interface to trusted internal addresses only and disable WAN-side administration
Change default and shared administrator credentials to reduce the risk of low-privilege session abuse
Audit existing accounts on affected devices and remove unused or unnecessary users
Place vulnerable devices behind a network segment that filters inbound HTTP traffic to /boafrm/* paths

Patch Information

At the time of publication, no vendor advisory or fixed firmware version was listed for CVE-2025-5737. Monitor the TOTOLINK security page for updated firmware addressing the /boafrm/formDosCfg handler. Apply any released patch to firmware 1.0.0-B20230714.1105 as soon as it becomes available.

Workarounds

Disable remote management on the WAN interface through the router configuration
Use access control lists on upstream network equipment to block HTTP and HTTPS traffic to the router from untrusted sources
Where feasible, replace end-of-support or unpatched TOTOLINK X15 devices with hardware that receives active security maintenance
Segment IoT and network appliances onto a dedicated VLAN to limit lateral movement after a successful exploit

bash

# Example: block external access to the router management interface using iptables on an upstream gateway
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -i <wan_iface> -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -i <wan_iface> -j DROP