CVE-2025-6336 is a critical buffer overflow vulnerability identified in the TOTOLINK EX1200T router, specifically in version 4.1.2cu.5232_B20210713. The flaw exists within an unknown function handling HTTP POST requests to the /boafrm/formTmultiAP endpoint. The vulnerability arises from improper handling of the 'submit-url' argument, which can be manipulated by an attacker to trigger a buffer overflow condition. This type of vulnerability can lead to arbitrary code execution or cause the device to crash, impacting availability. The vulnerability is remotely exploitable without requiring user interaction or authentication, increasing the risk profile significantly. The CVSS 4.0 base score is 8.7 (high severity), with attack vector network (AV:N), low attack complexity (AC:L), no privileges required (PR:L), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (VC:H/VI:H/VA:H). Although no known exploits are currently observed in the wild, the public disclosure of the exploit code increases the likelihood of active exploitation. The vulnerability affects a specific firmware version of the TOTOLINK EX1200T, a consumer-grade wireless router commonly used in small offices and home environments. The buffer overflow in the HTTP POST request handler suggests that an attacker can send specially crafted HTTP requests to the device’s web management interface to compromise the system remotely. Given the critical nature of the flaw and the ease of exploitation, this vulnerability poses a significant threat to the security posture of affected devices, potentially allowing attackers to gain control over the router, intercept or manipulate network traffic, or disrupt network availability.

For European organizations, the exploitation of CVE-2025-6336 could have severe consequences. TOTOLINK EX1200T devices are often deployed in small to medium-sized enterprises (SMEs) and home office environments, which may lack robust security monitoring. Successful exploitation could lead to unauthorized access to internal networks, interception of sensitive communications, or disruption of internet connectivity. This is particularly concerning for organizations relying on these routers for VPN termination or remote access, as attackers could pivot into corporate networks. The compromise of router integrity undermines network security, potentially exposing confidential data and enabling further lateral movement by threat actors. Additionally, availability impacts could disrupt business operations, especially for SMEs that depend on stable internet connectivity. The public availability of exploit code increases the risk of opportunistic attacks, including automated scanning and exploitation by botnets or ransomware groups. Given the high impact on confidentiality, integrity, and availability, organizations using affected devices face a substantial risk of data breaches, service outages, and reputational damage.

1. Immediate firmware upgrade: Organizations should verify the firmware version of their TOTOLINK EX1200T devices and upgrade to a patched version once released by the vendor. If no patch is currently available, consider temporary mitigations such as disabling remote management interfaces or restricting access to the router’s web interface to trusted IP addresses only. 2. Network segmentation: Isolate affected routers from critical internal networks to limit the impact of a potential compromise. 3. Monitor network traffic: Deploy intrusion detection systems (IDS) or network monitoring tools to detect anomalous HTTP POST requests targeting /boafrm/formTmultiAP or unusual traffic patterns indicative of exploitation attempts. 4. Access control: Enforce strong administrative passwords and disable unnecessary services on the router to reduce attack surface. 5. Incident response readiness: Prepare to respond to potential exploitation by maintaining up-to-date backups and having a plan to replace or reconfigure compromised devices quickly. 6. Vendor engagement: Engage with TOTOLINK support channels to obtain information on patch availability and recommended security practices. 7. User awareness: Educate users about the risks of using outdated router firmware and encourage regular updates and security hygiene.