CVE-2025-11123 identifies a stack-based buffer overflow vulnerability in the Tenda AC18 router firmware version 15.03.05.19. The vulnerability resides in the /goform/saveAutoQos endpoint, specifically in the handling of the 'enable' parameter. Improper validation or bounds checking of this argument allows an attacker to overwrite the stack memory, potentially leading to arbitrary code execution. The vulnerability is remotely exploitable without requiring authentication or user interaction, making it highly accessible to attackers scanning for vulnerable devices exposed to the internet or internal networks. The CVSS 4.0 base score is 8.7, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges needed. While no confirmed exploits are currently active in the wild, a proof-of-concept exploit has been published, increasing the likelihood of exploitation attempts. The lack of an official patch at the time of disclosure means affected users must rely on network-level mitigations or vendor updates once available. This vulnerability could allow attackers to gain full control over the router, intercept or manipulate network traffic, and pivot to other internal systems, posing a significant threat to network security.

For European organizations, the impact of CVE-2025-11123 can be severe. The Tenda AC18 is commonly used in small office and home office environments, which are often less protected than enterprise-grade equipment. Exploitation could lead to full compromise of the router, enabling attackers to intercept sensitive communications, alter network configurations, or launch further attacks against internal systems. This could result in data breaches, disruption of business operations, and loss of trust. Critical infrastructure sectors relying on these devices for connectivity may face operational outages or espionage risks. The remote and unauthenticated nature of the exploit increases the attack surface, especially for organizations with exposed management interfaces or insufficient network segmentation. The absence of a patch at disclosure heightens the urgency for immediate mitigation to prevent exploitation. Overall, the vulnerability threatens confidentiality, integrity, and availability of network infrastructure within European organizations using affected devices.

1. Immediately restrict network access to the /goform/saveAutoQos endpoint by implementing firewall rules or access control lists that block external and unnecessary internal access to the router's management interface. 2. Monitor network traffic for unusual requests targeting the vulnerable endpoint, using intrusion detection systems or network behavior analysis tools. 3. Disable remote management features on the Tenda AC18 routers if not strictly necessary to reduce exposure. 4. Regularly check for and apply firmware updates from Tenda as soon as a patch addressing CVE-2025-11123 is released. 5. For environments where patching is delayed, consider deploying network segmentation to isolate vulnerable devices from critical systems. 6. Educate IT staff and users about the risks and signs of router compromise to enable rapid detection and response. 7. Maintain backups of router configurations to facilitate recovery in case of compromise. 8. Engage with Tenda support channels to obtain official guidance and updates regarding this vulnerability.