CVE-2025-11324 is a stack-based buffer overflow vulnerability discovered in the Tenda AC18 router firmware version 15.03.05.19(6318). The flaw exists in the handling of the 'newVersion' parameter within the /goform/setNotUpgrade endpoint, which is part of the router's web management interface. When an attacker sends a specially crafted request manipulating this argument, it causes a buffer overflow on the stack, enabling arbitrary code execution. The vulnerability is remotely exploitable without requiring authentication or user interaction, significantly increasing its risk profile. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P) indicates network attack vector, low complexity, no user interaction, and partial privileges required, with high impact on confidentiality, integrity, and availability. Although no active exploitation in the wild has been reported, a public exploit is available, which could facilitate rapid weaponization by threat actors. The vulnerability could allow attackers to take full control of affected devices, potentially pivoting into internal networks, intercepting or manipulating traffic, or launching further attacks. The lack of a vendor patch at the time of publication increases exposure. This vulnerability highlights the risks inherent in embedded device firmware and the critical need for timely updates and secure coding practices in IoT and networking equipment.

For European organizations, the impact of CVE-2025-11324 is substantial. The Tenda AC18 router is commonly deployed in small office and home office (SOHO) environments, which are often less rigorously secured than enterprise-grade infrastructure. Successful exploitation can lead to complete compromise of the router, allowing attackers to intercept, modify, or redirect network traffic, deploy malware, or establish persistent footholds within corporate or home networks. This can result in data breaches, disruption of business operations, and loss of sensitive information. Given the remote exploitability without authentication, attackers can target vulnerable devices en masse, potentially leading to large-scale network outages or botnet recruitment. European organizations relying on Tenda AC18 devices for critical connectivity or remote access are at heightened risk, especially if these devices are exposed to the internet or poorly segmented from internal networks. The vulnerability also poses risks to privacy and regulatory compliance under GDPR, as compromised routers can facilitate unauthorized data access or exfiltration.

1. Immediate action should be taken to check for firmware updates from Tenda addressing CVE-2025-11324; apply patches as soon as they become available. 2. Until patches are released, disable remote management interfaces on Tenda AC18 routers to reduce exposure to external attacks. 3. Implement network segmentation to isolate SOHO routers from sensitive internal networks, limiting lateral movement if a device is compromised. 4. Monitor network traffic for unusual patterns indicative of exploitation attempts, such as unexpected requests to /goform/setNotUpgrade. 5. Employ intrusion detection/prevention systems (IDS/IPS) with signatures targeting this vulnerability or exploit attempts. 6. Replace or upgrade vulnerable devices where possible, especially in high-risk environments. 7. Educate users and administrators about the risks of outdated firmware and the importance of timely updates. 8. Restrict access to router management interfaces to trusted IP addresses or VPN connections. 9. Conduct regular security audits of network devices to identify and remediate vulnerabilities proactively.