CVE-2021-20111 Explained : Impact and Mitigation

A stored cross-site scripting vulnerability exists in TCExam <= 14.8.1. An attacker with access to tce_filemanager.php could upload a malicious javascript payload which would be triggered when another user views the file.

Understanding CVE-2021-20111

This section delves into the details of CVE-2021-20111.

What is CVE-2021-20111?

CVE-2021-20111 is a stored cross-site scripting vulnerability found in TCExam <= 14.8.1. It allows an attacker to upload malicious code to be executed when another user interacts with the file.

The Impact of CVE-2021-20111

This vulnerability could lead to unauthorized script execution, potentially compromising the security and integrity of the system.

Technical Details of CVE-2021-20111

Let's explore the technical aspects of CVE-2021-20111.

Vulnerability Description

A stored XSS vulnerability in TCExam <= 14.8.1 allows attackers to upload malicious scripts via tce_filemanager.php, posing a risk of script execution.

Affected Systems and Versions

TCExam versions up to and including 14.8.1 are affected by this vulnerability.

Exploitation Mechanism

Attackers can exploit this vulnerability by uploading files with a filename starting with a period via tce_filemanager.php, which are then rendered as text/html, enabling execution of malicious payloads.

Mitigation and Prevention

Learn how to safeguard systems from CVE-2021-20111.

Immediate Steps to Take

Users should restrict access to tce_filemanager.php and avoid uploading files with filenames beginning with a period to mitigate the risk.

Long-Term Security Practices

Implement strong input validation, content security policies, and regular security audits to prevent stored XSS attacks.

Patching and Updates

It is crucial to update TCExam to a secure version beyond 14.8.1 to patch the vulnerability and protect the system from potential exploits.