CVE-2025-9748 is a high-severity stack-based buffer overflow vulnerability found in the Tenda CH22 router firmware version 1.0.0.1. The flaw exists in the function fromIpsecitem within the /goform/IPSECsave component of the embedded HTTP server (httpd). Specifically, the vulnerability arises from improper handling of the 'ipsecno' argument, which can be manipulated remotely by an unauthenticated attacker to trigger a stack-based buffer overflow. This type of vulnerability typically allows an attacker to overwrite adjacent memory on the stack, potentially leading to arbitrary code execution, denial of service, or system compromise. The CVSS 4.0 base score of 8.7 reflects the critical nature of this vulnerability, with network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L - low privileges, but no authentication needed), and no user interaction (UI:N). The vulnerability impacts confidentiality, integrity, and availability at a high level, as successful exploitation could allow remote code execution on the device. Although no known exploits are currently reported in the wild, the vulnerability is publicly disclosed and could be targeted by attackers once exploit code becomes available. The Tenda CH22 is a consumer and small office/home office (SOHO) router, and the vulnerability affects the IPsec VPN configuration interface, which is critical for secure remote connectivity. The lack of a published patch at this time increases the urgency for mitigation and risk management.

For European organizations, especially small and medium enterprises (SMEs) and home office users relying on Tenda CH22 routers for VPN connectivity, this vulnerability poses a significant risk. Exploitation could lead to unauthorized remote code execution, allowing attackers to intercept or manipulate VPN traffic, disrupt network availability, or pivot into internal networks. This could result in data breaches, loss of confidentiality of sensitive communications, and operational downtime. Given the widespread use of VPNs for secure remote access in Europe, especially in the context of remote work policies, the vulnerability could undermine trust in secure communications. Additionally, compromised routers could be leveraged as entry points for broader attacks or as part of botnets targeting European infrastructure. The absence of known exploits currently provides a window for proactive defense, but the high severity and ease of exploitation warrant immediate attention.

1. Immediate network segmentation: Isolate Tenda CH22 devices from critical internal networks to limit potential lateral movement if compromised. 2. Disable or restrict remote management interfaces, especially the IPsec VPN configuration web interface, to trusted IP addresses only. 3. Monitor network traffic for unusual activity or attempts to access /goform/IPSECsave endpoints. 4. Apply any vendor patches or firmware updates as soon as they become available; maintain close communication with Tenda for updates. 5. If patching is delayed, consider replacing affected devices with alternative routers from vendors with timely security support. 6. Employ intrusion detection/prevention systems (IDS/IPS) tuned to detect buffer overflow exploit attempts targeting Tenda routers. 7. Educate users about the risks of using vulnerable devices and encourage strong network hygiene practices. 8. Regularly audit VPN configurations and router firmware versions to ensure compliance with security policies.