CVE-2025-6149: Totolink A3002r Buffer Overflow Flaw

CVE-2025-6149 Overview

CVE-2025-6149 is a buffer overflow vulnerability affecting the TOTOLINK A3002R router running firmware version 4.0.0-B20230531.1404. The flaw resides in the HTTP POST request handler for the /boafrm/formSysLog endpoint. Attackers can trigger the overflow by manipulating the submit-url argument in a crafted HTTP POST request. The vulnerability is classified under [CWE-119] (improper restriction of operations within the bounds of a memory buffer) and can be exploited remotely. A public exploit disclosure exists, increasing the likelihood of opportunistic attacks against exposed devices.

Critical Impact
Remote attackers with low privileges can corrupt memory on the device, leading to denial of service or potential code execution on affected TOTOLINK A3002R routers.

Affected Products

TOTOLINK A3002R hardware device
TOTOLINK A3002R firmware version 4.0.0-B20230531.1404
HTTP POST request handler component (/boafrm/formSysLog)

Discovery Timeline

2025-06-17 - CVE-2025-6149 published to NVD
2025-06-23 - Last updated in NVD database

Technical Details for CVE-2025-6149

Vulnerability Analysis

The vulnerability exists in the web management interface of the TOTOLINK A3002R router. The /boafrm/formSysLog endpoint accepts HTTP POST requests containing a submit-url parameter. The underlying handler copies the supplied value into a fixed-size buffer without proper bounds checking. Supplying an overly long submit-url value overruns adjacent memory regions.

Because the affected binary runs as part of the router's boa web server, exploitation operates in the context of a privileged service. Successful memory corruption can crash the service, force a device reboot, or in worst-case scenarios allow attacker-controlled execution. The vulnerability requires authentication at a low privilege level but no user interaction.

Root Cause

The root cause is the absence of length validation on user-supplied input before copying it into a fixed-size stack or heap buffer. This is a classic [CWE-119] memory safety failure common in embedded web interfaces built around the boa HTTP server. The submit-url parameter is treated as trusted input and passed directly to a memory copy routine without enforcing a maximum length.

Attack Vector

An attacker reaches the vulnerable endpoint over the network by sending an HTTP POST request to /boafrm/formSysLog on the router's management interface. The attacker authenticates with low-privilege credentials and submits an oversized submit-url value. The malformed request triggers the overflow inside the request handler. Devices that expose the web administration interface to untrusted networks or the internet face the highest exposure.

The vulnerability mechanism is documented in the public proof-of-concept maintained at the GitHub PoC Repository. No verified exploitation code is reproduced here; refer to the linked advisory for technical details.

Detection Methods for CVE-2025-6149

Indicators of Compromise

HTTP POST requests targeting /boafrm/formSysLog containing unusually long submit-url parameter values
Unexpected reboots or crashes of the TOTOLINK A3002R web management service (boa)
Outbound connections from the router to unfamiliar hosts following anomalous POST traffic
Modifications to router configuration or DNS settings that do not match administrator activity

Detection Strategies

Inspect web server and firewall logs for POST requests to /boafrm/formSysLog originating from untrusted sources
Deploy network intrusion detection signatures that flag oversized parameter values directed at TOTOLINK management endpoints
Correlate router availability alerts with preceding HTTP traffic to identify exploitation attempts that cause service restarts

Monitoring Recommendations

Forward router syslog and HTTP access logs to a centralized analytics platform for retention and inspection
Alert on repeated authentication attempts against the router management interface from external IP ranges
Monitor for new administrative sessions established outside normal maintenance windows

How to Mitigate CVE-2025-6149

Immediate Actions Required

Restrict access to the router's web management interface to trusted internal management VLANs only
Disable remote (WAN-side) administration on affected TOTOLINK A3002R devices
Rotate administrator credentials and enforce strong passwords to limit the low-privilege access required for exploitation
Inventory all TOTOLINK A3002R units running firmware 4.0.0-B20230531.1404 and prioritize them for remediation

Patch Information

At the time of NVD publication, no vendor-supplied patch was referenced in the advisory. Administrators should monitor the Totolink Security Page for firmware updates addressing CVE-2025-6149. Additional vulnerability tracking is available at VulDB #312624.

Workarounds

Block inbound HTTP and HTTPS traffic to the router's management port from untrusted networks at the perimeter firewall
Place vulnerable routers behind a segmented management network accessible only via VPN
Consider replacing end-of-support TOTOLINK A3002R devices with actively maintained hardware if no patch becomes available

bash

# Example: restrict management interface access using an upstream firewall (iptables)
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -s <mgmt_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -s <mgmt_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -j DROP