CVE-2025-25610 Overview
CVE-2025-25610 is a buffer overflow vulnerability in the TOTOlink A3002R router running firmware version V1.1.1-B20200824.0128. The flaw resides in the formIpv6Setup interface of the /bin/boa web server binary. The router fails to validate the length of the static_gw parameter before copying it into a fixed-size buffer. An authenticated attacker on an adjacent network can send a crafted request to trigger memory corruption, potentially leading to arbitrary code execution or device compromise. The vulnerability is classified under CWE-120 (Classic Buffer Overflow).
Critical Impact
Successful exploitation allows an adjacent-network attacker with low privileges to compromise router confidentiality, integrity, and availability through memory corruption in the embedded web server.
Affected Products
- TOTOlink A3002R hardware device
- TOTOlink A3002R firmware version V1.1.1-B20200824.0128
- Devices exposing the formIpv6Setup interface via /bin/boa
Discovery Timeline
- 2025-02-28 - CVE-2025-25610 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-25610
Vulnerability Analysis
The vulnerability affects the formIpv6Setup handler within the /bin/boa web server on the TOTOlink A3002R router. This handler processes IPv6 configuration parameters submitted through the router's administrative web interface. The static_gw parameter, which is intended to hold the static IPv6 gateway address, is copied into a fixed-size stack buffer without proper bounds checking.
When an attacker submits an oversized static_gw value, the copy operation overwrites adjacent stack memory. This corruption can overwrite the saved return address on MIPS or ARM architectures typically used in these embedded devices. Attackers can leverage this control flow hijack to execute arbitrary code within the context of the boa process, which typically runs with root privileges on embedded routers.
The attack requires access to the adjacent network and low-level authenticated privileges. Once obtained, exploitation grants full device control.
Root Cause
The root cause is improper input validation of user-supplied data. The formIpv6Setup function does not verify the length of the static_gw parameter before invoking an unsafe string copy operation such as strcpy or sprintf. This omission allows attacker-controlled data to exceed the destination buffer boundary and corrupt adjacent memory regions.
Attack Vector
An attacker positioned on the same network segment as the router must first authenticate to the administrative interface. The attacker then submits a crafted HTTP POST request to the formIpv6Setup endpoint containing an oversized static_gw parameter. The oversized value triggers the stack overflow inside /bin/boa, allowing the attacker to hijack execution flow.
See the TOTOLINK A3002R formIpv6Setup static_gw analysis for technical details on the vulnerable code path.
// No verified proof-of-concept code available.
// See the external technical reference for detailed analysis of the vulnerable code path in /bin/boa.
Detection Methods for CVE-2025-25610
Indicators of Compromise
- Unexpected crashes or reboots of the boa web server process on TOTOlink A3002R devices
- HTTP POST requests to /formIpv6Setup containing abnormally long static_gw parameter values
- Unauthorized modification of router IPv6 configuration or firmware
- Outbound connections from the router to unfamiliar external hosts, indicating post-exploitation activity
Detection Strategies
- Inspect HTTP traffic to the router administrative interface for requests targeting formIpv6Setup with oversized parameter values
- Monitor router system logs for repeated authentication attempts followed by web server crashes
- Deploy network intrusion detection signatures that flag HTTP requests exceeding expected parameter length for IPv6 configuration fields
Monitoring Recommendations
- Restrict access to the router administrative interface to trusted management VLANs only
- Log and alert on all configuration changes to the formIpv6Setup endpoint
- Track device availability and process stability metrics to identify exploitation attempts that cause service disruption
How to Mitigate CVE-2025-25610
Immediate Actions Required
- Isolate affected TOTOlink A3002R devices from untrusted network segments and restrict management access to a dedicated administrative VLAN
- Change default administrative credentials and enforce strong, unique passwords to raise the barrier for authenticated exploitation
- Disable IPv6 configuration functionality if it is not required in the deployment environment
- Audit connected devices to identify any TOTOlink A3002R units running firmware V1.1.1-B20200824.0128
Patch Information
No vendor advisory or patched firmware release has been published in the NVD reference set at the time of writing. Organizations should monitor the TOTOlink support portal for firmware updates addressing the formIpv6Setup input validation flaw and apply them as soon as they are available.
Workarounds
- Block external and untrusted internal access to the router's web administration interface using upstream firewall rules
- Place vulnerable devices behind a network segmentation boundary that requires VPN or bastion access for management
- Consider replacing the affected device with a supported model if the vendor does not release a firmware update
# Example firewall rule to restrict router admin access to a management subnet
iptables -A INPUT -p tcp --dport 80 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
