CVE-2025-53715 is a medium-severity vulnerability affecting the TP-Link TL-WR841N V11 router. The issue stems from improper input validation in the /userRpm/Wan6to4TunnelCfgRpm.htm web interface file, which leads to a buffer overflow condition. Specifically, the vulnerability is classified under CWE-119, indicating improper restriction of operations within the bounds of a memory buffer. An attacker can exploit this flaw remotely without user interaction or authentication, by sending specially crafted requests to the vulnerable web service. Successful exploitation causes a buffer overflow that crashes the web service, resulting in a denial-of-service (DoS) condition. This disrupts the router’s normal operation, potentially cutting off network connectivity for users relying on this device. Notably, the affected product is no longer supported by the vendor, meaning no official patches or updates are available to remediate the vulnerability. The CVSS 4.0 base score is 6.9, reflecting a medium severity level due to the remote attack vector, lack of required user interaction, but the requirement for high privileges (PR:H) to exploit it. The vulnerability does not impact confidentiality, integrity, or availability beyond the DoS effect on the web service component. No known exploits are currently reported in the wild. This vulnerability highlights risks associated with legacy network devices that remain in operation without vendor support, exposing organizations to unpatched security flaws that can disrupt network infrastructure.

For European organizations, the primary impact of CVE-2025-53715 is the potential denial-of-service on network routers using the TP-Link TL-WR841N V11 model. This can lead to temporary loss of internet connectivity or internal network disruptions, affecting business operations, communications, and access to cloud or online services. Since the device is a consumer-grade or small office/home office (SOHO) router, the impact is more pronounced in smaller organizations or remote offices that rely on this hardware without replacement or upgrades. The lack of vendor support means organizations cannot obtain patches, increasing exposure duration. In critical environments, such as healthcare, manufacturing, or financial sectors, even short network outages can have operational and compliance consequences. Additionally, the vulnerability could be leveraged as part of a broader attack chain to degrade network availability or distract security teams. However, the requirement for high privileges to exploit the vulnerability limits the risk of widespread exploitation by external attackers without prior access. Overall, the threat underscores the importance of inventorying and replacing unsupported network infrastructure to maintain security and availability.

Given the absence of official patches, European organizations should prioritize the following mitigations: 1) Identify and inventory all TP-Link TL-WR841N V11 devices in their networks, focusing on remote or branch office locations where legacy equipment is common. 2) Replace unsupported routers with currently supported models that receive security updates from the vendor. 3) If immediate replacement is not feasible, restrict access to the router’s web management interface by implementing network segmentation and firewall rules to limit exposure to trusted management hosts only. 4) Disable remote management features on the affected devices to prevent external exploitation attempts. 5) Monitor network traffic and device logs for unusual activity targeting the /userRpm/Wan6to4TunnelCfgRpm.htm endpoint or signs of web service crashes. 6) Educate IT staff about the risks of unsupported hardware and establish policies to phase out end-of-life devices proactively. 7) Consider deploying network-level DoS mitigation controls to reduce impact if exploitation attempts occur. These steps go beyond generic advice by focusing on compensating controls and asset lifecycle management tailored to this specific vulnerability and device type.