CVE-2025-13288 is a buffer overflow vulnerability identified in the Tenda CH22 router firmware version 1.0.0.1. The flaw exists in the function fromPptpUserSetting, specifically in the handling of the 'delno' parameter within the /goform/PPTPUserSetting HTTP endpoint. An attacker can remotely send a crafted request manipulating the 'delno' argument to overflow a buffer, potentially overwriting memory and enabling arbitrary code execution or causing a denial of service. The vulnerability requires no authentication or user interaction, making it highly exploitable over the network. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (C:H, I:H, A:H). Although no exploits have been observed in the wild yet, the public disclosure of the vulnerability and technical details increases the likelihood of exploitation attempts. The vulnerability affects only version 1.0.0.1 of the Tenda CH22 firmware, a device commonly used in small office and home office environments for VPN and broadband connectivity. The lack of available patches at the time of disclosure necessitates interim mitigations to prevent exploitation.

The exploitation of CVE-2025-13288 can lead to full compromise of affected Tenda CH22 routers, allowing attackers to execute arbitrary code remotely. This can result in unauthorized access to network traffic, interception or manipulation of data, disruption of network services, and potential pivoting into internal networks. For European organizations, especially small and medium enterprises relying on Tenda CH22 devices for VPN or broadband connectivity, this vulnerability poses a significant risk to network security and business continuity. The compromise of these routers could lead to data breaches involving sensitive customer or corporate information, disruption of critical business operations, and potential regulatory non-compliance under GDPR due to inadequate protection of personal data. The ease of exploitation without authentication or user interaction further elevates the threat level, making automated attacks feasible. Additionally, the lack of patches at disclosure time increases exposure duration.

1. Immediately restrict external network access to the /goform/PPTPUserSetting endpoint by implementing firewall rules or access control lists to block unsolicited inbound traffic targeting the router's management interfaces. 2. Disable PPTP VPN functionality on the Tenda CH22 device if not required, reducing the attack surface. 3. Monitor network traffic for anomalous requests to the vulnerable endpoint and unusual router behavior indicative of exploitation attempts. 4. Apply vendor-provided firmware updates or patches as soon as they become available to remediate the vulnerability. 5. If patching is delayed, consider isolating affected devices within segmented network zones with limited access to critical infrastructure. 6. Employ intrusion detection/prevention systems (IDS/IPS) with signatures targeting exploitation attempts of this vulnerability. 7. Educate network administrators about the vulnerability and ensure incident response plans include steps for compromised router scenarios. 8. Regularly audit and update router firmware and configurations to maintain security hygiene.