CVE-2019-12581 Explained : Impact and Mitigation

A reflective Cross-site scripting (XSS) vulnerability in Zyxel ZyWall, USG, and UAG devices allows remote attackers to inject arbitrary web script or HTML via the err_msg parameter.

Understanding CVE-2019-12581

What is CVE-2019-12581?

The free_time_failed.cgi CGI program in specific Zyxel devices is vulnerable to reflective Cross-site scripting (XSS) attacks, enabling malicious actors to insert arbitrary web script or HTML by exploiting the err_msg parameter.

The Impact of CVE-2019-12581

This vulnerability poses a significant risk as it allows remote attackers to execute malicious scripts on affected devices, potentially leading to unauthorized access, data theft, or further exploitation of the system.

Technical Details of CVE-2019-12581

Vulnerability Description

The free_time_failed.cgi CGI program in certain Zyxel ZyWall, USG, and UAG devices contains a reflective Cross-site scripting (XSS) vulnerability, which can be exploited by remote attackers to inject malicious web script or HTML via the err_msg parameter.

Affected Systems and Versions

Product: Not applicable
Vendor: Not applicable
Versions: Not applicable

Exploitation Mechanism

The vulnerability in the free_time_failed.cgi CGI program allows attackers to inject arbitrary web script or HTML by manipulating the err_msg parameter, potentially leading to XSS attacks.

Mitigation and Prevention

Immediate Steps to Take

Disable the affected CGI program or apply vendor-supplied patches promptly.
Implement network-level controls to filter out malicious input and prevent XSS attacks.

Long-Term Security Practices

Regularly update and patch all Zyxel devices to mitigate known vulnerabilities.
Conduct security assessments and penetration testing to identify and address potential security weaknesses.

Patching and Updates

Stay informed about security advisories from Zyxel and apply patches as soon as they are released to ensure the protection of your devices.