CVE-2025-55847 is a high-severity buffer overflow vulnerability identified in the Wavlink M86X3A_V240730 device, specifically within the /cgi-bin/ExportAllSettings.cgi endpoint. The vulnerability stems from improper validation of the length of the Cookie parameter input. Buffer overflow vulnerabilities occur when a program writes more data to a buffer than it can hold, potentially overwriting adjacent memory. In this case, the lack of proper input length validation allows an attacker to craft a malicious Cookie parameter that can overflow the buffer. This overflow can be exploited to execute arbitrary code on the affected device or cause a denial of service (DoS) by crashing the system. The vulnerability does not require authentication or user interaction, increasing its risk profile. The CVSS 3.1 base score of 8.8 reflects its high impact on confidentiality, integrity, and availability, with an attack vector over the network (AV:A - adjacent network), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The vulnerability is classified under CWE-120 (Classic Buffer Overflow). Although no known exploits are currently reported in the wild, the potential for remote code execution or DoS makes this a critical issue for affected devices. The absence of patch links suggests that a fix may not yet be publicly available, emphasizing the need for immediate mitigation and monitoring.

For European organizations using Wavlink M86X3A_V240730 devices, this vulnerability poses significant risks. Exploitation could lead to unauthorized remote code execution, allowing attackers to gain control over network devices, potentially pivoting to internal networks, exfiltrating sensitive data, or disrupting network services. The DoS potential could impair critical network infrastructure, affecting business continuity and operational availability. Given the device's role likely in networking or IoT contexts, compromised devices could serve as entry points for broader attacks or be leveraged in botnets. The lack of authentication and user interaction requirements means attackers can exploit this vulnerability remotely and stealthily, increasing the threat to enterprise and industrial environments. This is particularly concerning for sectors with high reliance on network stability and data confidentiality, such as finance, healthcare, and critical infrastructure within Europe.

Organizations should immediately inventory their network to identify any Wavlink M86X3A_V240730 devices. Until an official patch is released, network-level mitigations should be applied: restrict access to the device management interfaces to trusted IP ranges using firewall rules; disable or restrict access to the /cgi-bin/ExportAllSettings.cgi endpoint if possible; implement network segmentation to isolate vulnerable devices from critical systems; monitor network traffic for unusual requests targeting the vulnerable CGI endpoint or anomalous Cookie header lengths; employ intrusion detection/prevention systems (IDS/IPS) with custom signatures to detect exploitation attempts. Additionally, coordinate with Wavlink support or vendors for updates on patches or firmware upgrades. Regularly review device logs for signs of exploitation attempts. As a longer-term measure, consider replacing vulnerable devices with models that have a stronger security posture and timely patch support.