CVE-2021-31355 : What You Need to Know

An informative article detailing the Stored Cross-Site Scripting (XSS) vulnerability in the captive portal of Juniper Networks Junos OS.

Understanding CVE-2021-31355

This vulnerability allows a remote authenticated user to inject web script or HTML, potentially compromising sensitive data on affected devices.

What is CVE-2021-31355?

A persistent XSS vulnerability in the captive portal interface of Juniper Networks Junos OS that may lead to the theft of sensitive data and credentials during web administration sessions.

The Impact of CVE-2021-31355

The vulnerability poses a high severity risk, enabling an attacker to execute unauthorized administrative actions on affected devices.

Technical Details of CVE-2021-31355

Detailed information on the vulnerability affecting various versions of Junos OS.

Vulnerability Description

The vulnerability allows for the injection of malicious scripts or HTML code during an authenticated web session, leading to potential data theft.

Affected Systems and Versions

Juniper Networks Junos OS versions prior to 21.2R1, including popular releases like 12.3X48, 15.1X49, and 20.4R2.

Exploitation Mechanism

The vulnerability can be exploited by injecting web scripts through the captive portal interface, potentially leading to unauthorized administrative actions.

Mitigation and Prevention

Understanding how to mitigate the risks associated with CVE-2021-31355 and prevent exploitation.

Immediate Steps to Take

Upgrade affected devices to the latest patched versions provided by Juniper Networks and remove any stored malicious scripts from the configuration.

Long-Term Security Practices

Regularly update and patch Junos OS to prevent known vulnerabilities and maintain a secure network environment.

Patching and Updates

Ensure all relevant security patches are applied promptly to mitigate the risk of XSS vulnerabilities like CVE-2021-31355.