CVE-2020-8155 : What You Need to Know

An outdated 3rd party library in the Files PDF viewer for Nextcloud Server 18.0.2 caused a Cross-site scripting vulnerability when opening a malicious PDF.

Understanding CVE-2020-8155

This CVE involves a Cross-site scripting vulnerability in Nextcloud Server 18.0.3 due to an outdated 3rd party library in the Files PDF viewer.

What is CVE-2020-8155?

CVE-2020-8155 is a Cross-site scripting vulnerability in Nextcloud Server 18.0.3, allowing attackers to execute malicious scripts in a user's browser.

The Impact of CVE-2020-8155

This vulnerability could be exploited by attackers to perform various malicious actions, such as stealing sensitive information, session hijacking, or defacing websites.

Technical Details of CVE-2020-8155

This section provides more in-depth technical details about the vulnerability.

Vulnerability Description

The vulnerability in Nextcloud Server 18.0.3 is caused by an outdated 3rd party library in the Files PDF viewer, enabling Cross-site scripting attacks when a user opens a malicious PDF.

Affected Systems and Versions

Affected Product: Nextcloud Server
Affected Version: 18.0.3

Exploitation Mechanism

Attackers can exploit this vulnerability by crafting a malicious PDF file and tricking a user into opening it within the vulnerable Nextcloud Server environment.

Mitigation and Prevention

To address CVE-2020-8155 and enhance security, follow these mitigation strategies:

Immediate Steps to Take

Update Nextcloud Server to the latest version that includes a patch for this vulnerability.
Educate users about the risks of opening files from untrusted sources.

Long-Term Security Practices

Regularly update and patch all software components to prevent known vulnerabilities.
Implement Content Security Policy (CSP) to mitigate Cross-site scripting attacks.

Patching and Updates

Ensure timely installation of security patches and updates provided by Nextcloud to address vulnerabilities like CVE-2020-8155.