CVE-2021-46144 : Exploit Details and Defense Strategies

Roundcube before 1.4.13 and 1.5.x before 1.5.2 allows XSS via an HTML e-mail message with crafted Cascading Style Sheets (CSS) token sequences.

Understanding CVE-2021-46144

What is CVE-2021-46144?

Roundcube versions prior to 1.4.13 and 1.5.x before 1.5.2 are vulnerable to cross-site scripting (XSS) attacks when processing HTML e-mail messages containing specially crafted CSS token sequences.

The Impact of CVE-2021-46144

This vulnerability could allow an attacker to execute malicious scripts in the context of a user's session, potentially leading to unauthorized actions such as stealing sensitive information or performing actions on behalf of the user.

Technical Details of CVE-2021-46144

Vulnerability Description

The vulnerability in Roundcube versions before 1.4.13 and 1.5.x before 1.5.2 exists due to insufficient sanitization of CSS token sequences in HTML e-mail messages, enabling XSS attacks.

Affected Systems and Versions

Roundcube versions prior to 1.4.13
Roundcube versions prior to 1.5.2

Exploitation Mechanism

Attackers can exploit this vulnerability by sending a specially crafted HTML e-mail containing malicious CSS token sequences to a vulnerable Roundcube instance, leading to the execution of arbitrary scripts in the user's context.

Mitigation and Prevention

Immediate Steps to Take

Update Roundcube to version 1.4.13 if using a version prior to this release.
Update Roundcube to version 1.5.2 if using a version prior to this release.
Exercise caution while opening HTML e-mails, especially from untrusted sources.

Long-Term Security Practices

Enforce strict input validation and output encoding practices in web applications.
Implement Content Security Policy (CSP) to mitigate XSS vulnerabilities.

Patching and Updates

Regularly monitor security advisories from Roundcube and apply patches promptly to address known vulnerabilities.