CVE-2025-57069 is a high-severity vulnerability identified in the Tenda G3 router firmware version 3.0br_V15.11.0.17. The flaw is a stack overflow occurring in the handling of the pPppUser parameter within the getsinglepppuser function. Specifically, this vulnerability arises when a crafted request with maliciously formed input is sent to the device, causing the function to write beyond the allocated stack buffer. This leads to a Denial of Service (DoS) condition, effectively crashing or rebooting the router and disrupting network connectivity. The vulnerability does not require any authentication or user interaction, and can be exploited remotely over the network (AV:N), with low attack complexity (AC:L). The impact is limited to availability (A:H), with no confidentiality or integrity compromise indicated. The vulnerability is classified under CWE-121, which corresponds to a classic stack-based buffer overflow. No public exploits are known to be in the wild at this time, and no patches or mitigations have been officially released. The CVSS v3.1 base score is 7.5, reflecting the high impact on availability combined with ease of exploitation and remote attack vector. This vulnerability could be leveraged by attackers to disrupt critical network infrastructure relying on Tenda G3 routers, causing service outages and operational interruptions.

For European organizations, the impact of this vulnerability can be significant, especially for small and medium enterprises or branch offices that utilize Tenda G3 routers for internet connectivity or internal network routing. A successful exploitation would result in denial of service, causing network downtime and loss of productivity. Critical sectors such as finance, healthcare, and manufacturing could experience operational disruptions, potentially affecting business continuity. Additionally, organizations relying on these routers for remote access or VPN services may lose connectivity, impacting remote workforce operations. Although the vulnerability does not allow data theft or manipulation, the availability impact alone can lead to financial losses and reputational damage. Given the remote and unauthenticated nature of the exploit, attackers could launch automated attacks at scale, increasing the risk of widespread outages. European organizations with limited IT security resources may face challenges in detecting and mitigating such attacks promptly.

Since no official patches are currently available, European organizations should implement immediate compensating controls. Network administrators should isolate vulnerable Tenda G3 routers from untrusted networks and restrict access to management interfaces using firewall rules or network segmentation. Monitoring network traffic for unusual or malformed PPP requests targeting the pPppUser parameter can help detect exploitation attempts. Employing intrusion detection/prevention systems (IDS/IPS) with custom signatures for this vulnerability is recommended. Organizations should consider replacing affected devices with updated hardware or firmware versions once patches are released. Regularly auditing network devices for outdated firmware and maintaining an asset inventory will facilitate rapid response. Additionally, applying strict access control policies and disabling unnecessary services on the routers can reduce the attack surface. Coordination with Tenda for timely updates and subscribing to vulnerability advisories will ensure organizations remain informed about remediation progress.