CVE-2026-26736 identifies a stack-based buffer overflow vulnerability in the TOTOLINK A3002RU_V3 router firmware version V3.0.0-B20220304.1804. The vulnerability resides in the formIpv6Setup function, specifically triggered by the static_ipv6 parameter. A stack-based buffer overflow occurs when input data exceeds the buffer's allocated size on the call stack, potentially overwriting adjacent memory, including return addresses or control data. This can allow an attacker to execute arbitrary code with the privileges of the affected process or cause a denial of service by crashing the device. The vulnerability is exploitable remotely if an attacker can send crafted requests to the router’s management interface that processes the static_ipv6 parameter, likely via the web interface or API. No authentication requirements are detailed, which may imply that exploitation could be possible without credentials if the interface is exposed. No known exploits have been reported in the wild, and no patches or vendor advisories are currently available. The absence of a CVSS score limits precise severity quantification, but the technical nature of the flaw suggests a critical security risk. The vulnerability affects a specific firmware version, indicating that other versions may not be vulnerable or remain untested. The exploitability depends on network exposure of the router’s management interface and the ability of an attacker to send maliciously crafted IPv6 configuration data. Given the router’s role in network infrastructure, successful exploitation could compromise network confidentiality, integrity, and availability.

For European organizations, exploitation of this vulnerability could lead to significant security incidents. Successful attacks may result in unauthorized remote code execution, allowing attackers to gain control over the router, intercept or manipulate network traffic, and pivot to internal networks. This could compromise sensitive data confidentiality and integrity. Additionally, denial of service conditions could disrupt network availability, affecting business operations and critical services. Organizations relying on TOTOLINK A3002RU_V3 routers in their network infrastructure, especially in sectors such as telecommunications, government, finance, and critical infrastructure, face elevated risks. The lack of patches increases exposure time, and the potential for exploitation without authentication or user interaction heightens the threat. Network segmentation and exposure of router management interfaces to untrusted networks could exacerbate impact severity. The vulnerability also poses risks to home office environments where such routers may be used, potentially serving as entry points into corporate networks via VPN or remote access.

1. Immediately restrict access to the router’s management interface by limiting it to trusted internal networks and disabling remote management where possible. 2. Implement strict firewall rules to block unauthorized access to router configuration ports and services, especially from external networks. 3. Monitor network traffic for unusual or malformed IPv6 configuration requests targeting the static_ipv6 parameter. 4. Employ network segmentation to isolate vulnerable devices from critical systems and sensitive data. 5. Regularly audit and inventory network devices to identify the presence of TOTOLINK A3002RU_V3 routers running the vulnerable firmware version. 6. Engage with the vendor for firmware updates or patches and apply them promptly once available. 7. Consider deploying intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics to detect exploitation attempts targeting this vulnerability. 8. Educate network administrators about the vulnerability and enforce strong authentication and access control policies for device management. 9. If possible, replace vulnerable devices with models that have no known vulnerabilities or have received timely security updates.