CVE-2025-5629 is a critical buffer overflow vulnerability found in the Tenda AC10 router firmware versions up to 15.03.06.47. The flaw exists in the HTTP handler component, specifically in the function formSetPPTPServer within the /goform/SetPptpServerCfg endpoint. This function processes the startIp and endIp parameters, and improper handling of these arguments leads to a buffer overflow condition. Because the vulnerable endpoint is accessible remotely and does not require user interaction or elevated privileges, an attacker can exploit this flaw over the network without authentication. The buffer overflow can potentially allow an attacker to execute arbitrary code on the device, leading to full compromise of the router. This could enable attackers to intercept, manipulate, or redirect network traffic, launch further attacks on internal networks, or create persistent backdoors. The vulnerability has a CVSS 4.0 score of 8.7 (high severity) with the vector indicating network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. Although no public exploits are currently known in the wild, the vulnerability details have been disclosed, increasing the risk of exploitation. The affected versions cover a wide range of firmware releases, indicating that many deployed devices remain vulnerable if not updated. The lack of available patches at the time of disclosure further elevates the threat level.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and small-to-medium businesses relying on Tenda AC10 routers for network connectivity. Successful exploitation can lead to unauthorized access to internal networks, data interception, and disruption of network services. Given the router's role as a gateway device, attackers could pivot to other critical infrastructure or sensitive systems within the organization. The compromise of network integrity and confidentiality could result in data breaches, regulatory non-compliance (e.g., GDPR violations), and operational downtime. Additionally, the availability impact could disrupt business continuity. The remote and unauthenticated nature of the exploit increases the attack surface, making it easier for threat actors to target vulnerable devices across Europe. Organizations with remote or hybrid workforces using these routers at branch offices or home offices are particularly at risk. The public disclosure of the vulnerability also raises the likelihood of automated scanning and exploitation attempts by opportunistic attackers.

1. Immediate firmware upgrade: Organizations should monitor Tenda's official channels for security patches addressing CVE-2025-5629 and apply updates promptly once available. 2. Network segmentation: Isolate vulnerable Tenda AC10 devices from critical network segments to limit potential lateral movement in case of compromise. 3. Access control: Restrict remote management interfaces and block access to the /goform/SetPptpServerCfg endpoint from untrusted networks using firewall rules or router ACLs. 4. Disable PPTP server functionality if not required, as this reduces the attack surface related to the vulnerable function. 5. Continuous monitoring: Deploy network intrusion detection systems (NIDS) to detect anomalous traffic patterns targeting the vulnerable endpoint. 6. Device replacement: For environments where patching is delayed or unsupported, consider replacing Tenda AC10 routers with devices from vendors with robust security update practices. 7. Incident response readiness: Prepare to isolate and remediate compromised devices quickly, including backup configurations and device inventories to facilitate rapid recovery.