CVE-2025-6151 in TL-WR940N V4
Summary
by MITRE • 06/17/2025
A vulnerability has been found in TP-Link TL-WR940N V4 and TL-WR841N V11. Affected by this issue is some unknown functionality of the file /userRpm/WanSlaacCfgRpm.htm, which may lead to buffer overflow. The attack may be launched remotely. This vulnerability only affects products that are no longer supported by the maintainer.
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Analysis
by VulDB Data Team • 07/16/2025
The vulnerability identified as CVE-2025-6151 represents a critical buffer overflow condition within the TP-Link TL-WR940N V4 and TL-WR841N V11 router models, specifically affecting the /userRpm/WanSlaacCfgRpm.htm file component. This issue resides within the web-based management interface of these devices, which serves as the primary attack vector for exploitation. The affected firmware versions have reached end-of-life status, meaning they no longer receive security updates or patches from the vendor, significantly increasing the risk exposure for affected users. The buffer overflow vulnerability stems from inadequate input validation within the web application layer, where user-supplied data is processed without proper bounds checking mechanisms. This particular implementation flaw allows an attacker to craft malicious input that exceeds the allocated buffer space, potentially causing memory corruption and arbitrary code execution within the router's operating environment.
The technical exploitation of this vulnerability occurs through remote network access, making it particularly dangerous for devices connected to public networks or exposed to the internet. Attackers can leverage this weakness by sending specially crafted HTTP requests to the vulnerable web interface, targeting the specific endpoint associated with the WAN SLAAC configuration functionality. The nature of the buffer overflow allows for potential privilege escalation and complete system compromise, as the affected router operates with elevated privileges to manage network configurations. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and may also relate to CWE-787, representing out-of-bounds write vulnerabilities. The attack surface is further expanded by the fact that these routers typically serve as the primary gateway for home and small office networks, making them attractive targets for adversaries seeking persistent access to larger network environments.
The operational impact of CVE-2025-6151 extends beyond simple device compromise, as affected routers can become part of botnet networks or serve as pivoting points for lateral movement within compromised networks. The lack of vendor support for these models means that organizations cannot rely on official patches or security updates, leaving them vulnerable to exploitation by threat actors who may have already developed working exploits for this specific flaw. Network administrators should consider the implications of this vulnerability in environments where these devices remain operational, as they may inadvertently provide attackers with persistent access to critical network infrastructure. The vulnerability's remote exploitation capability means that attackers do not require physical access to the device, enabling widespread compromise from any location with internet connectivity. This threat is particularly concerning given the widespread deployment of these router models and the typical lack of network segmentation that might otherwise limit the damage.
Security mitigation strategies for this vulnerability should focus on immediate network isolation of affected devices, as patching is not possible due to end-of-life status. Organizations should implement network segmentation to prevent these devices from directly accessing critical internal systems, and consider replacing the affected hardware with supported models from the vendor or alternative security-focused routers. Network monitoring should be enhanced to detect anomalous traffic patterns that might indicate exploitation attempts, particularly targeting the specific web interface ports and endpoints. The vulnerability demonstrates the importance of maintaining up-to-date firmware and avoiding deployment of unsupported network equipment, as these devices often remain vulnerable to known exploits long after their initial release. Additionally, implementing network access controls and disabling unnecessary services on these devices can help reduce the attack surface, while regular security assessments should be conducted to identify and remediate similar vulnerabilities in other network infrastructure components. This case highlights the broader cybersecurity challenge of managing legacy network equipment and underscores the critical need for comprehensive inventory management and regular security audits to identify and address such exposure risks.