CVE-2021-43776 Explained : Impact and Mitigation

Backstage is an open platform for building developer portals. The XSS vulnerability in affected versions of the auth-backend plugin can lead to malicious attacks.

Understanding CVE-2021-43776

In this CVE, a Cross-Site Scripting (XSS) vulnerability in the @backstage/plugin-auth-backend plugin allows malicious actors to execute attacks by tricking users into visiting a vulnerable URL.

What is CVE-2021-43776?

Backstage is an open platform where the auth-backend plugin in certain versions is vulnerable to an XSS attack. An attacker can exploit this by directing a user to a compromised URL, potentially leading to data theft.

The Impact of CVE-2021-43776

The vulnerability has a CVSS v3.1 base score of 7.4, with high severity. It can result in the exfiltration of sensitive information, such as access tokens, from the user's browser.

Technical Details of CVE-2021-43776

This section delves into the specific technical aspects of the vulnerability

Vulnerability Description

The XSS vulnerability in @backstage/plugin-auth-backend allows for unauthorized execution of scripts, posing a risk of data theft.

Affected Systems and Versions

Affected Product: Backstage
Vulnerable Versions: < 0.4.9

Exploitation Mechanism

Attack Complexity: Low
Attack Vector: Network
User Interaction: Required
Confidentiality Impact: High
Integrity Impact: None
Privileges Required: None

Mitigation and Prevention

To address the CVE-2021-43776 vulnerability, follow these steps:

Immediate Steps to Take

Upgrade @backstage/plugin-auth-backend to version 0.4.9
Implement Content Security Policy (CSP) to mitigate XSS attacks

Long-Term Security Practices

Regularly update and patch software to the latest versions
Educate users on safe browsing habits

Patching and Updates

Ensure all systems and plugins are kept up to date to prevent potential vulnerabilities.