The vulnerability identified as CVE-2025-57070 affects the Tenda G3 router running firmware version 3.0br_V15.11.0.17. It is a stack overflow vulnerability located in the gstUp parameter within the guestWifiRuleRefresh function. A stack overflow occurs when more data is written to a buffer located on the stack than it can hold, which can overwrite adjacent memory and lead to unpredictable behavior. In this case, the vulnerability allows an attacker to send a crafted request that triggers the overflow, causing the device to crash or become unresponsive, resulting in a Denial of Service (DoS). The vulnerability does not mention any exploitation of code execution or privilege escalation, and no known exploits are currently in the wild. The absence of a CVSS score indicates that the vulnerability has been recently published and not yet fully assessed. The gstUp parameter is likely part of the guest Wi-Fi management functionality, which may be exposed to local or possibly remote attackers depending on the router's configuration and network exposure. The stack overflow in this context primarily impacts availability by crashing the device or disrupting its normal operation. Since no authentication or user interaction requirements are specified, it is possible that exploitation could be performed remotely if the vulnerable function is accessible externally or via the guest Wi-Fi network. No patch or mitigation details are currently available, which suggests that affected users should be cautious and monitor for vendor updates.

For European organizations, the impact of this vulnerability could be significant depending on the deployment of Tenda G3 routers within their network infrastructure. The primary impact is a Denial of Service, which can disrupt internet connectivity, guest Wi-Fi access, or other network services relying on the affected device. This could lead to operational downtime, loss of productivity, and potential disruption of business-critical communications. Organizations that provide guest Wi-Fi services to customers or employees may experience service interruptions, affecting user experience and trust. Additionally, if the device is used in smaller branch offices or remote sites, the DoS could isolate these locations from the corporate network, complicating IT support and incident response. While the vulnerability does not currently indicate data breach or code execution risks, the disruption of network availability can have cascading effects on security monitoring, remote access, and business continuity. European organizations should consider the potential for targeted attacks exploiting this vulnerability, especially in sectors where network uptime is critical, such as finance, healthcare, and public services.

Given the lack of an official patch or vendor advisory, European organizations should implement the following specific mitigation steps: 1) Immediately identify and inventory all Tenda G3 routers, particularly those running firmware version 3.0br_V15.11.0.17, within their network environment. 2) Restrict access to the guest Wi-Fi management interface by implementing network segmentation and firewall rules to limit exposure to trusted internal networks only. 3) Disable guest Wi-Fi functionality temporarily if it is not essential, or restrict guest network access to minimize attack surface. 4) Monitor network traffic for unusual or malformed requests targeting the guestWifiRuleRefresh function or related endpoints, using intrusion detection systems or network behavior analysis tools. 5) Establish heightened monitoring for router stability and availability to detect early signs of exploitation attempts. 6) Engage with Tenda support channels to obtain information about forthcoming patches or firmware updates addressing this vulnerability. 7) Prepare incident response plans to quickly isolate and remediate affected devices in case of exploitation. 8) Consider deploying alternative network equipment from vendors with timely security update practices if the risk is deemed unacceptable.