Overview
In today’s cybersecurity landscape, a notable vulnerability has been discovered, identified as CVE-2025-45865. This vulnerability affects TOTOLINK A3002R v4.0.0-B20230531.1404, a popular networking device widely used by businesses and individuals worldwide. The vulnerability is related to a buffer overflow condition tied to the ‘dnsaddr’ parameter in the ‘formDhcpv6s’ interface. Given the widespread usage of this device, this vulnerability poses a significant risk, as it may potentially lead to system compromise or data leakage.
Vulnerability Summary
CVE ID: CVE-2025-45865
Severity: Critical (9.8 CVSS score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage
Affected Products
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Product | Affected Versions
TOTOLINK A3002R | v4.0.0-B20230531.1404
How the Exploit Works
The exploit works by sending an oversized ‘dnsaddr’ parameter to the ‘formDhcpv6s’ interface of the TOTOLINK A3002R. This results in a buffer overflow condition, allowing the attacker to execute arbitrary code. This can lead to a complete system compromise and potentially expose sensitive data to the attacker.
Conceptual Example Code
Here’s a conceptual example of how the vulnerability might be exploited. This example illustrates an HTTP POST request that contains a malicious payload designed to exploit the buffer overflow vulnerability.
POST /formDhcpv6s HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "dnsaddr": "A long string that causes a buffer overflow..." }This request would trigger the buffer overflow condition, thereby potentially allowing the attacker to execute arbitrary code on the vulnerable system.
Mitigation
Users of the affected TOTOLINK A3002R version are strongly advised to apply the vendor patch as soon as it becomes available. In the interim, the use of a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can provide temporary mitigation. These systems can be configured to block or alert on attempts to exploit this vulnerability. Despite these temporary measures, the most effective mitigation strategy is to apply the vendor’s patch to completely eliminate the vulnerability.