CVE-2025-61128 is a stack-based buffer overflow vulnerability identified in the firmware version M30HG3_V240730 of the WAVLINK QUANTUM D3G/WL-WN530HG3 router models, with potential impact on other WAVLINK models. The flaw exists in the handling of the HTTP POST request to the login.cgi endpoint, specifically when processing the referrer header value. An attacker can craft a malicious referrer value that overflows the stack buffer, enabling arbitrary code execution remotely without requiring authentication or user interaction. This vulnerability is classified under CWE-121 (Stack-based Buffer Overflow), which typically allows attackers to overwrite return addresses or function pointers, leading to control over the execution flow. The CVSS v3.1 score of 9.1 reflects the vulnerability's critical nature, with network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality and availability, though integrity impact is rated none. Successful exploitation could allow attackers to take full control over the affected device, disrupt network services, intercept or manipulate traffic, and potentially pivot to internal networks. No patches or firmware updates have been published yet, and no active exploits have been reported, but the vulnerability's characteristics make it a high-risk target for attackers. The vulnerability's presence in consumer and possibly enterprise-grade routers increases the attack surface, especially in environments where these devices are deployed as gateways or access points.

For European organizations, the impact of CVE-2025-61128 can be severe. Compromise of WAVLINK routers could lead to unauthorized remote code execution, resulting in loss of confidentiality through interception of network traffic, disruption of availability by causing device crashes or network outages, and potential lateral movement within corporate networks. Critical infrastructure sectors such as finance, healthcare, and government agencies relying on these devices for secure connectivity could face operational disruptions and data breaches. The lack of authentication and user interaction requirements lowers the barrier for exploitation, increasing the risk of widespread attacks. Additionally, the vulnerability could be leveraged for launching further attacks such as man-in-the-middle, data exfiltration, or establishing persistent footholds. The absence of patches means organizations must rely on network-level mitigations and monitoring until firmware updates are available. The threat is particularly relevant for small and medium enterprises and remote offices that commonly deploy consumer-grade routers like WAVLINK devices due to cost considerations.

1. Immediately identify and inventory all WAVLINK QUANTUM D3G/WL-WN530HG3 and other potentially affected models within the network. 2. Isolate vulnerable devices from critical network segments and restrict management interface access to trusted IP addresses only. 3. Implement network-level protections such as Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) to detect and block malicious POST requests targeting login.cgi with suspicious referrer headers. 4. Monitor network traffic and device logs for unusual POST requests or signs of exploitation attempts. 5. Disable remote management interfaces if not strictly necessary, or restrict them via VPN or secure tunnels. 6. Engage with WAVLINK support or vendors to obtain firmware updates or patches as soon as they become available. 7. Consider replacing vulnerable devices with models from vendors with a stronger security track record if immediate patching is not feasible. 8. Educate IT staff on the vulnerability details and ensure incident response plans include steps for potential exploitation scenarios. 9. Apply network segmentation to limit the impact of compromised devices on broader organizational infrastructure.