CVE-2021-39250 : What You Need to Know

Invision Community (aka IPS Community Suite or IP-Board) before 4.6.5.1 allows stored XSS, with resultant code execution, due to security vulnerabilities in user-generated content. This CVE poses a serious threat as it enables an attacker to execute malicious code by exploiting various admin capabilities.

Understanding CVE-2021-39250

This section provides insights into the nature and impact of the CVE.

What is CVE-2021-39250?

CVE-2021-39250 is a security vulnerability in Invision Community, allowing stored XSS that can lead to code execution. By leveraging certain admin privileges and session vulnerabilities, an attacker can compromise the system.

The Impact of CVE-2021-39250

The exploitation of this CVE can result in severe consequences:

Execution of arbitrary code through uploaded files in an IFRAME element within user-generated content
Possibility of code execution by exploiting admin capabilities like installing widgets and utilizing the templating engine

Technical Details of CVE-2021-39250

Exploring the vulnerability and its technical aspects.

Vulnerability Description

The vulnerability in Invision Community before version 4.6.5.1 allows stored XSS, enabling an attacker to execute code via an uploaded file placed in an IFRAME within user-generated content.

Affected Systems and Versions

Affected System: Invision Community (aka IPS Community Suite or IP-Board)
Vulnerable Versions: Before 4.6.5.1

Exploitation Mechanism

The attacker can exploit the vulnerability through these means:

Utilizing the ability of an admin to install widgets
Disclosing the admin session ID in a Referer header
Leveraging the admin's capability to use the templating engine

Mitigation and Prevention

Understanding how to mitigate and prevent the exploitation of CVE-2021-39250.

Immediate Steps to Take

To address this CVE promptly, consider the following actions:

Update Invision Community to version 4.6.5.1 or above
Restrict admin privileges to minimize the impact of potential attacks
Monitor system logs for any suspicious activities

Long-Term Security Practices

For lasting security, implement these practices:

Conduct regular security audits to detect vulnerabilities
Train admins and users on secure practices to prevent XSS attacks
Implement web application firewalls to filter and block malicious traffic

Patching and Updates

Regularly apply security patches and updates provided by the vendor to safeguard the system from known vulnerabilities.