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Summary

A newly discovered buffer overflow vulnerability, designated as CVE-2025-25896, has been found in D-Link DSL-3782 v1.01 routers. This vulnerability allows malicious actors to potentially execute a Denial of Service (DoS) attack through specially crafted packets. The flaw lies within the handling of the destination, netmask, and gateway parameters.

Vulnerability Details

D-Link DSL-3782 v1.01 is a popular router used in many home and small business networks. The vulnerability was uncovered in the handling of destination, netmask, and gateway parameters, which if exploited, could allow an attacker to cause a buffer overflow leading to a DoS attack.

The cause of the vulnerability stems from the way the router processes certain packets. When a packet containing oversized destination, netmask, and gateway parameters is sent to the router, it fails to handle the packet properly and overflows the buffer, potentially resulting in a crash that would disable the device for a period of time.

Here's a simple code snippet illustrating the issue

#include <stdio.h>
#include <string.h>

void vulnerable_function(char *data) {
    char buf[256];
    strcpy(buf, data);
}

int main(int argc, char *argv[]) {
    char exploit_data[512];
    
    // Fill exploit_data with malicious oversized packet
    memset(exploit_data, '\x41', sizeof(exploit_data)-1);
    exploit_data[sizeof(exploit_data)-1] = '\';
    
    vulnerable_function(exploit_data);
    
    return ;
}

The vulnerable function copies the provided data into a buffer without checking if it will fit. In this case, the exploit_data array is twice the size of the buf array, causing the buffer overflow to occur.

Exploitation

This vulnerability can be exploited by adversaries using a crafted packet that contains oversized destination, netmask, and gateway parameters. Once the router processes the packet, the buffer overflow will occur, resulting in a DoS condition.

Though no public exploits have been released at the time of writing, users must stay vigilant and apply any available security patches or firmware updates as they are released by D-Link.

Mitigation

As of now, it is unclear whether D-Link has released a patch addressing CVE-2025-25896. Users are strongly advised to monitor D-Link's website for any security updates or communications related to this vulnerability.

In the meantime, users can take these precautions to reduce the risk of exploitation

1. Restrict external access to the router's administrative interface and ensure the router's default credentials are changed to a secure username and password.

- CVE-2025-25896 - Official Listing
- D-Link Firmware and Support
- CVE-2025 Series Vulnerabilities by Common Vulnerabilities and Exposures (CVE®)


In conclusion, CVE-2025-25896 poses a serious threat to users of D-Link DSL-3782 v1.01 routers. By exploiting this buffer overflow vulnerability, attackers can potentially execute DoS attacks, leaving networks inaccessible for an extended period. Users must remain vigilant and apply patches or firmware updates as soon as they become available.

Timeline

Published on: 02/18/2025 22:15:19 UTC
Last modified on: 02/19/2025 16:15:42 UTC