CVE-2025-5854 is a critical buffer overflow vulnerability identified in the Tenda AC6 router firmware version 15.03.05.16. The flaw exists in the function fromadvsetlanip within the /goform/AdvSetLanip endpoint. Specifically, the vulnerability arises from improper handling of the lanMask argument, which can be manipulated by an attacker to cause a buffer overflow condition. This type of vulnerability can lead to memory corruption, potentially allowing remote attackers to execute arbitrary code or cause a denial of service on the affected device. The vulnerability is remotely exploitable without requiring user interaction or prior authentication, increasing its risk profile. The CVSS v4.0 score is 8.7 (high severity), reflecting the ease of exploitation (network attack vector, low complexity), no privileges or user interaction needed, and a high impact on confidentiality, integrity, and availability. Although no known exploits are currently observed in the wild, the public disclosure of the exploit code increases the likelihood of active exploitation attempts. The Tenda AC6 is a consumer-grade wireless router commonly used in home and small office environments, and the vulnerable function relates to LAN IP configuration settings, which are critical for network operation and security. Exploitation could allow attackers to gain control over the router, intercept or manipulate network traffic, or pivot into internal networks.

For European organizations, especially small businesses and home office users relying on Tenda AC6 routers, this vulnerability poses a significant risk. Compromise of these routers can lead to unauthorized network access, interception of sensitive data, and disruption of network services. In environments where these routers serve as the primary gateway to the internet, attackers could establish persistent footholds, launch further attacks against internal systems, or exfiltrate confidential information. Given the critical nature of the vulnerability and the lack of authentication requirements, attackers can remotely exploit devices exposed to the internet or accessible within local networks. This threat is particularly concerning for sectors with sensitive data such as finance, healthcare, and government agencies operating in decentralized or remote settings. Additionally, the potential for widespread exploitation could disrupt internet connectivity for affected users, impacting business continuity and operational efficiency.

1. Immediate firmware update: Organizations and users should verify if Tenda has released a patched firmware version addressing CVE-2025-5854 and apply it promptly. 2. Network segmentation: Isolate vulnerable Tenda AC6 devices from critical internal networks to limit potential lateral movement in case of compromise. 3. Access control: Restrict remote management access to the router, preferably disabling WAN-side administration or limiting it to trusted IP addresses. 4. Monitor network traffic: Deploy intrusion detection systems (IDS) or network monitoring tools to detect anomalous activity targeting the /goform/AdvSetLanip endpoint or unusual LAN IP configuration changes. 5. Replace legacy devices: Consider replacing Tenda AC6 routers with models from vendors with strong security track records and timely patch management. 6. User awareness: Educate users about the risks of exposing router management interfaces and encourage regular firmware checks. 7. Firewall rules: Implement firewall rules to block unsolicited inbound traffic to router management ports from untrusted networks.