CVE-2022-44256 is a recent security vulnerability discovered in TOTOLINK's LR350 router, specifically in the firmware version V9.3.5u.6369_B20220309. This critical flaw involves a post-authentication buffer overflow vulnerability, and if exploited, it can cause significant harm to the targeted device or network. In this post, we will examine the technical aspects of this vulnerability in detail, discuss the exploitation process, and provide code snippets and references for further understanding.

Vulnerability Details

The vulnerability stems from an issue in one of the router's functions where it doesn't properly validate user input, leading to a buffer overflow attack. Specifically, the flaw lies within the 'setLanguageCfg' function that takes the 'lang' parameter as input. An attacker with post-authentication access can leverage this vulnerability to remotely execute arbitrary code or crash the device.

Here's the code snippet showcasing the problematic function

int setLanguageCfg(void* arg) {
    char lang[18];
    if (get_request_var("lang", lang, sizeof(lang)) == -1) {
        return -1;

The 'get_request_var' function is responsible for receiving and processing user input. It takes three parameters: the user input name, the storage variable, and the storage length. In this case, the variable 'lang' has a fixed length of 18, which should ideally not allow the input size to surpass the allocated buffer length. However, there is no proper input validation process in place, allowing an attacker to submit a malicious payload via the 'lang' parameter that exceeds the buffer length and triggers the buffer overflow.


To exploit this vulnerability, an attacker must first have post-authentication access to the targeted TOTOLINK LR350 device. This could be achieved by discovering the login credentials or other authentication bypass methods.

Once authenticated, the attacker can send a specifically crafted HTTP request containing an oversized 'lang' parameter to the '/goform/setLanguageCfg' endpoint:

POST /goform/setLanguageCfg HTTP/1.1
Content-Type: application/x-www-form-urlencoded
Content-Length: 104


By sending this request, the attacker overflows the 'lang' buffer, overwriting adjacent memory locations and potentially executing arbitrary code in the context of the vulnerable process.

Protection and Mitigation

To mitigate the risk posed by this vulnerability, it is strongly recommended to update the router's firmware to the latest version or apply a security patch when it becomes available. Additionally, tightening access controls to the administration interface and employing strong, unique passwords can reduce the likelihood of an attacker achieving post-authentication access.


CVE-2022-44256 is a critical post-authentication buffer overflow vulnerability in TOTOLINK LR350's firmware version V9.3.5u.6369_B20220309. Attackers with post-authentication access can exploit this vulnerability, potentially executing arbitrary code or crashing the targeted device. To protect against exploitation, users should update their router's firmware, apply security patches, and enforce strong access controls.

Original References

- CVE-2022-44256 - NIST National Vulnerability Database (NVD)
- TOTOLINK Official Website
- OWASP - Buffer Overflow


Published on: 11/23/2022 16:15:00 UTC
Last modified on: 11/26/2022 03:44:00 UTC