CVE-2021-27705 : What You Need to Know

A Buffer Overflow vulnerability in Tenda G1 and G3 routers with firmware v15.11.0.17(9502)_CN allows remote attackers to execute arbitrary code via a crafted request, posing a significant security risk.

Understanding CVE-2021-27705

This section delves into the details of the CVE-2021-27705 vulnerability affecting Tenda routers.

What is CVE-2021-27705?

The CVE-2021-27705 vulnerability involves a Buffer Overflow issue in Tenda G1 and G3 routers with specific firmware, enabling attackers to trigger malicious code execution by exploiting a flaw in the 'formQOSRuleDel' function.

The Impact of CVE-2021-27705

The exploitation of this vulnerability could lead to unauthorized remote code execution on affected Tenda routers, jeopardizing the confidentiality, integrity, and availability of the targeted devices and network.

Technical Details of CVE-2021-27705

This section elucidates the technical specifics of CVE-2021-27705.

Vulnerability Description

The vulnerability stems from the insecure handling of user input in the 'formQOSRuleDel' function, where the 'qosIndex' parameter is passed to 'strcpy' without proper boundary checks, resulting in a Buffer Overflow condition.

Affected Systems and Versions

Tenda G1 and G3 routers running firmware version v15.11.0.17(9502)_CN are susceptible to this vulnerability.

Exploitation Mechanism

Remote attackers can exploit this flaw by sending a specially crafted request containing a malicious 'qosIndex' parameter, leveraging it to execute arbitrary code on the target device.

Mitigation and Prevention

To address CVE-2021-27705, immediate action and long-term security measures are crucial.

Immediate Steps to Take

Users are advised to update their Tenda G1 and G3 routers to the latest firmware version provided by the vendor and restrict network access to vulnerable devices.

Long-Term Security Practices

Implementing network segmentation, strong access controls, and regular security assessments can enhance overall network security posture.

Patching and Updates

Regularly check for firmware updates and security advisories from Tenda to apply patches promptly and safeguard against known vulnerabilities.