CVE-2025-13258 is a buffer overflow vulnerability identified in the Tenda AC20 router firmware versions up to 16.03.08.12. The vulnerability exists in an unspecified function within the /goform/WifiExtraSet endpoint, specifically triggered by manipulation of the wpapsk_crypto parameter. This parameter is improperly validated, allowing an attacker to overflow a buffer remotely. The vulnerability requires no authentication or user interaction, making it highly accessible to remote attackers. Exploitation could enable arbitrary code execution, potentially allowing attackers to gain full control over the router, disrupt network traffic, or pivot into internal networks. The CVSS 4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with low attack complexity and no privileges required. Although no active exploitation has been reported, a public exploit is available, increasing the urgency for mitigation. The lack of official patches at the time of reporting necessitates interim protective measures. The vulnerability affects all firmware versions from 16.03.08.0 through 16.03.08.12, indicating a broad exposure for users of this product line.

For European organizations, exploitation of this vulnerability could lead to severe consequences including unauthorized access to internal networks, interception or manipulation of sensitive data, disruption of business operations due to network outages, and potential lateral movement by attackers within corporate environments. Given that routers serve as critical network gateways, compromise could undermine perimeter defenses and facilitate further attacks such as data exfiltration or ransomware deployment. Small and medium enterprises (SMEs) and public sector entities using Tenda AC20 devices are particularly vulnerable due to potentially limited cybersecurity resources. The availability of a public exploit increases the likelihood of targeted attacks or opportunistic scanning campaigns within Europe. Additionally, critical infrastructure sectors relying on these routers for connectivity may face operational risks, impacting service continuity and regulatory compliance.

Organizations should immediately inventory their network to identify any Tenda AC20 devices running vulnerable firmware versions. Until an official patch is released, network administrators should restrict remote access to these devices by implementing firewall rules that limit management interface exposure to trusted IP addresses only. Disabling remote management features and isolating affected routers on segmented network zones can reduce attack surface. Monitoring network traffic for unusual activity targeting the /goform/WifiExtraSet endpoint can provide early detection of exploitation attempts. Once Tenda releases a firmware update addressing this vulnerability, prompt application of the patch is critical. Additionally, organizations should consider deploying intrusion prevention systems (IPS) with signatures targeting this exploit and conduct user awareness training to recognize potential signs of network compromise. Regular backups of router configurations and network devices will aid in recovery if compromise occurs.