CVE-2021-46871 Explained : Impact and Mitigation

A vulnerability in Phoenix.HTML allows XSS in HEEx class attributes.

Understanding CVE-2021-46871

What is CVE-2021-46871?

CVE-2021-46871 is a vulnerability in Phoenix Phoenix.HTML (aka phoenix_html) before version 3.0.4 that enables XSS attacks in HEEx class attributes.

The Impact of CVE-2021-46871

This vulnerability could allow an attacker to execute malicious scripts in the context of a user's browser, leading to unauthorized access to sensitive information or unauthorized actions.

Technical Details of CVE-2021-46871

Vulnerability Description

The vulnerability resides in the handling of class attributes in Phoenix.HTML, potentially allowing an attacker to inject and execute malicious scripts through crafted class attributes.

Affected Systems and Versions

Vendor: n/a
Product: n/a
Versions Affected: All versions before 3.0.4

Exploitation Mechanism

The vulnerability can be exploited by crafting malicious class attributes that contain executable script code which gets executed in the context of a user's browser when processed.

Mitigation and Prevention

Immediate Steps to Take

Update Phoenix.HTML to version 3.0.4 or later to mitigate the vulnerability.
Avoid clicking on suspicious links or visiting untrusted websites to prevent potential exploitation.

Long-Term Security Practices

Regularly update software and applications to ensure the latest security patches are applied.
Implement a Content Security Policy (CSP) to mitigate the risks of cross-site scripting (XSS) attacks.

Patching and Updates

Ensure timely patching and updates of Phoenix.HTML and other related software to address security vulnerabilities.