CVE-2025-5738: Totolink X15 Buffer Overflow Vulnerability

CVE-2025-5738 Overview

CVE-2025-5738 is a buffer overflow vulnerability in the TOTOLINK X15 router running firmware version 1.0.0-B20230714.1105. The flaw resides in the /boafrm/formStats endpoint of the HTTP POST Request Handler. Attackers can manipulate the submit-url argument to trigger memory corruption [CWE-119]. The issue is remotely exploitable across the network and the exploit details have been publicly disclosed. The vulnerability requires low privileges and no user interaction, exposing the device to compromise of confidentiality, integrity, and availability.

Critical Impact
Remote attackers with low privileges can overflow a buffer in the TOTOLINK X15 web interface, potentially leading to arbitrary code execution or denial of service on the affected router.

Affected Products

TOTOLINK X15 hardware device
TOTOLINK X15 firmware version 1.0.0-B20230714.1105
Network deployments exposing the device HTTP management interface

Discovery Timeline

2025-06-06 - CVE-2025-5738 published to the National Vulnerability Database
2025-06-17 - Last updated in NVD database

Technical Details for CVE-2025-5738

Vulnerability Analysis

The vulnerability is a classic buffer overflow [CWE-119] in the embedded web server of the TOTOLINK X15 router. The affected component is the HTTP POST Request Handler exposed through the /boafrm/formStats URI. When the device parses POST data, the submit-url parameter is copied into a fixed-size buffer without proper bounds checking. An attacker submitting an oversized value corrupts adjacent memory regions on the stack or heap.

Memory corruption in boa-based embedded web servers commonly results in process crashes or attacker-controlled execution flow. The TOTOLINK X15 runs the affected service with elevated privileges, so successful exploitation can grant control over networking, DNS settings, and traffic routing. The exploit details are public, lowering the barrier to weaponization. The EPSS probability of 0.601% reflects current observed exploitation likelihood, but public disclosure typically increases scanning activity.

Root Cause

The root cause is missing length validation when the formStats handler reads the submit-url POST parameter into a stack or heap buffer. The handler uses an unbounded copy routine such as strcpy or sprintf instead of length-limited equivalents. No input sanitization or maximum length enforcement is applied before the copy operation.

Attack Vector

Attacks originate over the network against the router's HTTP management interface. The adversary sends a crafted POST request to /boafrm/formStats containing an overlong submit-url value. Authentication at a low privilege level is required, which is satisfied on devices with default or weak credentials. The vulnerability mechanism is described in the linked GitHub Security Analysis and the VulDB entry #311264.

Detection Methods for CVE-2025-5738

Indicators of Compromise

POST requests to /boafrm/formStats containing unusually long submit-url parameter values
Unexpected reboots, crashes, or restarts of the boa web server process on the router
Outbound connections from the router to unfamiliar IP addresses following HTTP interaction
Unauthorized changes to DNS, routing, or firewall configuration

Detection Strategies

Inspect HTTP request logs on perimeter devices for POST traffic targeting /boafrm/formStats with parameter lengths exceeding normal admin interface usage
Deploy intrusion detection signatures that flag oversized POST bodies sent to TOTOLINK management URIs
Monitor SNMP, syslog, or device health metrics for repeated httpd crashes that indicate exploitation attempts

Monitoring Recommendations

Restrict and log all access to the router web administration interface and alert on access from non-management VLANs
Centralize router logs in a SIEM and correlate authentication events with /boafrm/ URI access patterns
Track firmware versions across the fleet to identify devices still running 1.0.0-B20230714.1105

How to Mitigate CVE-2025-5738

Immediate Actions Required

Remove the TOTOLINK X15 web management interface from internet-facing exposure and restrict it to a trusted management network
Change default and weak administrative credentials to prevent low-privilege attackers from reaching the vulnerable handler
Audit the device for unauthorized configuration changes, including DNS, routing rules, and remote management settings
Segment vulnerable routers from sensitive internal assets until a firmware update is applied

Patch Information

At the time of publication, no vendor advisory or firmware fix from TOTOLINK has been published in the referenced sources. Administrators should monitor the TOTOLINK official site for firmware updates addressing the formStats handler and apply them as soon as they become available.

Workarounds

Disable remote HTTP/HTTPS administration on the WAN interface and require LAN-side or VPN access for configuration
Place the router behind an upstream firewall that blocks POST requests to /boafrm/formStats from untrusted sources
Replace affected devices with supported hardware if no patch is released within an acceptable risk window

bash

# Example: block external access to the vulnerable URI at an upstream firewall (iptables)
iptables -A FORWARD -p tcp --dport 80 -m string \
  --string "/boafrm/formStats" --algo bm -j DROP
iptables -A FORWARD -p tcp --dport 443 -m string \
  --string "/boafrm/formStats" --algo bm -j DROP