CVE-2021-42659 : Exploit Details and Defense Strategies

A buffer overflow vulnerability in the Web server httpd of Tenda router devices can lead to a crash when handling super-long list parameters.

Understanding CVE-2021-42659

This CVE involves a critical buffer overflow issue in Tenda router devices.

What is CVE-2021-42659?

The vulnerability exists in the Web server httpd of Tenda routers like Tenda AC9 V1.0 V15.03.02.19(6318) and Tenda AC9 V3.0 V15.03.06.42_multi. It causes the httpd program to crash during the configuration of virtual services with excessively long list parameters.

The Impact of CVE-2021-42659

The vulnerability allows attackers to potentially crash the httpd service, leading to a denial of service (DoS) condition. This could disrupt network services and impact the router's availability.

Technical Details of CVE-2021-42659

This section details the technical aspects of the CVE.

Vulnerability Description

A buffer overflow vulnerability in the httpd service of Tenda routers can be exploited by malicious actors to crash the program.

Affected Systems and Versions

Tenda AC9 V1.0 V15.03.02.19(6318)
Tenda AC9 V3.0 V15.03.06.42_multi

Exploitation Mechanism

The vulnerability is triggered when handling virtual service configurations with long list parameters, causing the httpd service to crash.

Mitigation and Prevention

Protecting systems from CVE-2021-42659 is crucial for network security.

Immediate Steps to Take

Apply security patches provided by the vendor promptly.
Monitor network traffic for any unusual activity that might indicate an exploit attempt.

Long-Term Security Practices

Regularly update router firmware to the latest version.
Implement network segmentation to isolate critical devices.

Patching and Updates

Vendor-supplied patches should be applied as soon as they are available to mitigate the vulnerability effectively.