CVE-2020-36321 Explained : Impact and Mitigation

CVE-2020-36321, discovered on November 26, 2020, involves a directory traversal vulnerability in Vaadin versions 14.0.0 through 14.4.2 and 15.0.0 through 18.0.0. Attackers can exploit this flaw to access arbitrary files outside the intended frontend resources folder.

Understanding CVE-2020-36321

This section provides insights into the nature and impact of the CVE-2020-36321 vulnerability.

What is CVE-2020-36321?

CVE-2020-36321 is an improper URL validation vulnerability in the development mode handler of Vaadin's flow-server. It affects versions 2.0.0 through 2.4.1 (Vaadin 14.0.0 through 14.4.2) and 3.0 through 5.0 (Vaadin 15 through 18). This vulnerability allows attackers to request unauthorized files located outside the designated frontend resources folder.

The Impact of CVE-2020-36321

The vulnerability's impact is classified as medium severity with a CVSS base score of 5.9. The confidentiality of the affected systems is at high risk, while integrity and availability are not impacted. The attack complexity is high, and it can be exploited over a network without requiring user interaction.

Technical Details of CVE-2020-36321

Explore the technical aspects of CVE-2020-36321 to understand its implications and affected systems.

Vulnerability Description

The vulnerability arises from improper URL validation in the development mode handler of Vaadin's flow-server, enabling attackers to access unauthorized files outside the intended frontend resources folder.

Affected Systems and Versions

Vaadin versions 14.0.0 through 14.4.2 (flow-server 2.0.0 through 2.4.1) are impacted.
Vaadin versions 15.0.0 through 18.0.0 (flow-server 3.0.0 through 5.0.0) are also vulnerable.

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating URLs to access files stored outside the designated frontend resources folder.

Mitigation and Prevention

Learn how to mitigate the risks associated with CVE-2020-36321 and prevent potential exploitation.

Immediate Steps to Take

Update Vaadin to the latest patched version to eliminate the vulnerability.
Implement proper input validation and URL handling mechanisms to prevent directory traversal attacks.

Long-Term Security Practices

Regularly monitor and audit URL validation mechanisms in web applications.
Educate developers on secure coding practices to prevent similar vulnerabilities in the future.

Patching and Updates

Stay informed about security updates from Vaadin and apply patches promptly to secure your systems.