CVE-2025-57085 is a critical stack overflow vulnerability identified in the Tenda W30E router firmware version V16.01.0.19 (build 5037). The flaw exists in the UploadCfg function, specifically in the handling of the 'v17' parameter. An attacker can exploit this vulnerability by sending a specially crafted request that triggers a stack overflow condition. This overflow can lead to a Denial of Service (DoS) state, causing the device to crash or become unresponsive. The vulnerability is classified under CWE-121, which refers to classic stack-based buffer overflows, indicating improper bounds checking on input data. The CVSS v3.1 base score is 9.8, reflecting a critical severity level due to its network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). Although no known exploits have been reported in the wild yet, the ease of exploitation and the critical impact make it a significant threat. The absence of available patches at the time of publication increases the urgency for mitigation. The vulnerability affects the router’s firmware, which is a critical network infrastructure component, potentially impacting all devices running the vulnerable firmware version.

For European organizations, this vulnerability poses a substantial risk to network infrastructure stability and security. Tenda routers like the W30E are commonly used in small to medium enterprises and residential environments across Europe. Exploitation could lead to widespread Denial of Service conditions, disrupting internet connectivity and internal network communications. This can halt business operations, degrade productivity, and impact services relying on continuous network availability. Furthermore, the high impact on confidentiality and integrity suggests that, beyond DoS, there may be potential for attackers to manipulate or intercept sensitive data if the vulnerability is chained with other exploits. Critical sectors such as finance, healthcare, and government agencies in Europe could face operational disruptions and data breaches if their networks rely on vulnerable devices. The lack of authentication and user interaction requirements means attackers can remotely exploit this vulnerability without prior access, increasing the threat surface. Additionally, the potential for cascading failures in networked environments could amplify the impact across interconnected systems.

Immediate mitigation steps include isolating vulnerable Tenda W30E devices from critical network segments and restricting inbound access to the router’s management interfaces from untrusted networks. Network administrators should implement strict firewall rules to block unsolicited traffic targeting the UploadCfg function or related endpoints. Monitoring network traffic for anomalous requests resembling crafted exploit attempts is advisable. Since no official patches are available yet, organizations should consider temporary replacement of affected devices with alternative hardware or firmware versions not susceptible to this vulnerability. Employing network segmentation to limit the exposure of vulnerable routers and deploying intrusion detection/prevention systems (IDS/IPS) with updated signatures can help detect and block exploitation attempts. Regularly checking for firmware updates from Tenda and applying them promptly once released is critical. Additionally, organizations should conduct vulnerability assessments and penetration testing focused on network devices to identify and remediate similar issues proactively.