CVE-2025-5848 is a critical buffer overflow vulnerability identified in the Tenda AC15 router, specifically affecting firmware version 15.03.05.19_multi. The vulnerability resides in the HTTP POST request handler component, within the function formSetPPTPUserList located at /goform/setPptpUserList. The flaw arises from improper handling of the argument list passed to this function, which leads to a buffer overflow condition. This type of vulnerability allows an attacker to overwrite memory adjacent to the buffer, potentially enabling arbitrary code execution or causing a denial of service. The attack vector is remote and does not require user interaction or prior authentication, making exploitation more straightforward. The CVSS v4.0 base score is 8.7, indicating a high severity level, with metrics showing 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 (VC:H, VI:H, VA:H). Although no known exploits have been reported in the wild yet, the exploit code has been publicly disclosed, increasing the risk of imminent exploitation. The vulnerability is particularly dangerous because it targets a widely deployed consumer and small business router model, which often lacks robust security controls and timely patching. Successful exploitation could allow attackers to gain control over the device, intercept or manipulate network traffic, or pivot into internal networks.

For European organizations, the impact of this vulnerability could be significant, especially for small and medium enterprises (SMEs) and home office environments relying on Tenda AC15 routers for internet connectivity. Compromise of these routers can lead to unauthorized access to internal networks, interception of sensitive communications, and potential lateral movement to more critical systems. This could result in data breaches, disruption of business operations, and exposure to further malware infections or ransomware attacks. Given the high confidentiality, integrity, and availability impacts, organizations could face regulatory consequences under GDPR if personal data is compromised. Additionally, the lack of authentication requirement and ease of remote exploitation increase the risk of widespread attacks. The vulnerability could also be leveraged in botnet campaigns or as a foothold for advanced persistent threats targeting European infrastructure.

To mitigate this threat, European organizations should first identify any Tenda AC15 devices running the vulnerable firmware version 15.03.05.19_multi within their networks. Immediate steps include isolating these devices from critical network segments and restricting remote management access. Since no official patch links are currently available, organizations should monitor Tenda’s official channels for firmware updates addressing this vulnerability and apply them promptly once released. In the interim, network-level protections such as firewall rules blocking inbound HTTP POST requests to the /goform/setPptpUserList endpoint can reduce exposure. Deploying intrusion detection/prevention systems (IDS/IPS) with signatures for this vulnerability or exploit attempts can provide additional defense. Organizations should also enforce strong network segmentation, limit administrative access to trusted hosts, and conduct regular network traffic monitoring for unusual activity. Educating users about the risks of using outdated router firmware and encouraging timely updates is essential. Finally, consider replacing vulnerable devices with models from vendors with a strong security track record if patching is delayed.