CVE-2019-20920 : What You Need to Know

Handlebars versions prior to 3.0.8 and 4.x before 4.5.3 have a vulnerability that could lead to Arbitrary Code Execution. This vulnerability allows attackers to execute arbitrary JavaScript code through templates, posing a risk of Cross-Site Scripting (XSS) attacks.

Understanding CVE-2019-20920

Handlebars template engine versions prior to 3.0.8 and 4.x before 4.5.3 are susceptible to a critical security flaw that enables Arbitrary Code Execution.

What is CVE-2019-20920?

Handlebars versions before 3.0.8 and 4.x before 4.5.3 contain a vulnerability that arises from inadequate validation of templates, specifically due to the failure of the lookup helper. This flaw allows malicious actors to craft templates capable of executing arbitrary JavaScript code, potentially leading to Arbitrary Code Execution.

The Impact of CVE-2019-20920

Attackers can exploit this vulnerability to run arbitrary code on servers processing Handlebars templates or in victims' browsers, effectively executing Cross-Site Scripting (XSS) attacks.

Technical Details of CVE-2019-20920

Handlebars vulnerability details and affected systems.

Vulnerability Description

The lookup helper in Handlebars fails to properly validate templates, enabling attackers to submit templates that execute arbitrary JavaScript code, leading to potential Arbitrary Code Execution.

Affected Systems and Versions

Versions of Handlebars before 3.0.8 and 4.x prior to 4.5.3.

Exploitation Mechanism

Attackers can exploit this vulnerability by submitting malicious templates that execute arbitrary JavaScript code, allowing them to run arbitrary code on servers or victims' browsers.

Mitigation and Prevention

Protecting systems from CVE-2019-20920.

Immediate Steps to Take

Update Handlebars to version 3.0.8 or 4.5.3 or later to mitigate the vulnerability.
Implement input validation to prevent the execution of malicious templates.

Long-Term Security Practices

Regularly update software and libraries to patch known vulnerabilities.
Conduct security audits to identify and address potential security weaknesses.
Educate developers on secure coding practices to prevent similar vulnerabilities.

Patching and Updates

Apply patches and updates provided by Handlebars to address the vulnerability and enhance system security.