Overview
A critical vulnerability denominated CVE-2025-6151, has been publicly disclosed and poses a significant risk to TP-Link TL-WR940N V4 router users. This vulnerability affects an unknown functionality of the file /userRpm/WanSlaacCfgRpm.htm and could potentially lead to system compromise or data leakage. Due to the high severity of this vulnerability, it is crucial for users and administrators to understand the nature of this security flaw and take immediate steps to mitigate its impact.
Vulnerability Summary
CVE ID: CVE-2025-6151
Severity: Critical (CVSS: 8.8)
Attack Vector: Remote
Privileges Required: None
User Interaction: No user interaction required
Impact: Potential system compromise and data leakage
Affected Products
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Product | Affected Versions
TP-Link TL-WR940N | V4
How the Exploit Works
The vulnerability stems from an improper validation of the ‘dnsserver1’ argument within the /userRpm/WanSlaacCfgRpm.htm file. A remote attacker can exploit this vulnerability by sending a specifically crafted request that includes an oversized ‘dnsserver1’ argument. This triggers a buffer overflow condition in the router’s firmware leading to potential system compromise and data leakage.
Conceptual Example Code
The following is a conceptual example of how an attacker might exploit the vulnerability. Note that this is not a real exploit, but a representation of how the attack could theoretically occur.
GET /userRpm/WanSlaacCfgRpm.htm?dnsserver1=AAAAAAAA...[1K A's]...AAAA HTTP/1.1
Host: [Router IP]In this example, ‘AAAAAAAA…[1K A’s]…AAAA’ represents an oversized ‘dnsserver1’ argument that is sent to the vulnerable endpoint causing the buffer overflow.
Mitigation Guidance
Users are strongly advised to apply the vendor’s patch to fix this vulnerability. In case the patch cannot be immediately applied, use of a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as a temporary mitigation method. Additionally, users should consider disabling remote management of the router if it is not required, as the attack can be launched remotely.