Overview
A critical vulnerability, CVE-2025-4835, has been identified in TOTOLINK A702R, A3002R, and A3002RU routers. This vulnerability resides in an unknown functionality of the file /boafrm/formWlanRedirect of the HTTP POST Request Handler component. This vulnerability is particularly dangerous as attackers can exploit it remotely, potentially leading to a full system compromise or significant data leakage. Given the severity of the potential impact, it’s crucial for users and administrators of TOTOLINK routers to understand and address this vulnerability promptly.
Vulnerability Summary
CVE ID: CVE-2025-4835
Severity: Critical (CVSS: 8.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System Compromise, Data Leakage
Affected Products
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Product | Affected Versions
TOTOLINK A702R | 3.0.0-B20230809.1615
TOTOLINK A3002R | 3.0.0-B20230809.1615
TOTOLINK A3002RU | 3.0.0-B20230809.1615
How the Exploit Works
The vulnerability stems from improper handling of the ‘redirect-url’ argument in the HTTP POST Request Handler of the file /boafrm/formWlanRedirect. By manipulating this argument, an attacker can trigger a buffer overflow condition, potentially leading to execution of arbitrary code or causing the system to crash. Since the attack can be initiated remotely, an attacker does not need physical access to the device or valid user credentials to exploit this vulnerability.
Conceptual Example Code
This conceptual code shows a HTTP POST request that might be used to exploit the vulnerability. An attacker sends a maliciously crafted ‘redirect-url’ argument to the target router, leading to a buffer overflow.
POST /boafrm/formWlanRedirect HTTP/1.1
Host: target-router-ip
Content-Type: application/x-www-form-urlencoded
redirect-url=AAAAAAA...[long string]...In this example, the ‘redirect-url’ argument is filled with an excessively long string of ‘A’s, which can overflow the buffer and potentially execute malicious code.
Mitigation and Remediation
Users and administrators are advised to apply the vendor-provided patch as soon as possible. If immediate patching is not feasible, the use of a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can serve as temporary mitigation measures. These can help detect and block attempts to exploit this vulnerability. However, these are not long-term solutions and will not completely eliminate the risk. As such, the application of the vendor patch should be prioritized.