CVE-2021-20103 : Security Advisory and Response

Machform prior to version 16 is vulnerable to stored cross-site scripting due to insufficient sanitization of file attachments uploaded with forms through upload.php.

Understanding CVE-2021-20103

This CVE identifies a stored cross-site scripting vulnerability in AppNitro Machform versions prior to version 16, allowing attackers to execute malicious scripts.

What is CVE-2021-20103?

CVE-2021-20103 is a security flaw in Machform that occurs when file attachments uploaded with forms through upload.php are not properly sanitized, enabling the injection of malicious scripts.

The Impact of CVE-2021-20103

This vulnerability could be exploited by attackers to execute arbitrary code within the context of the user's browser, potentially leading to unauthorized data disclosure or account takeover.

Technical Details of CVE-2021-20103

The vulnerability lies in the insufficient sanitization of file attachments uploaded with forms through the upload.php script.

Vulnerability Description

The flaw allows for the storage of malicious scripts within file attachments, which can then be executed when accessed by other users.

Affected Systems and Versions

All versions of AppNitro Machform prior to version 16 are impacted by this vulnerability.

Exploitation Mechanism

Attackers can upload a form with a malicious file attachment containing a script, which is then stored by Machform. When other users access this attachment, the script is executed in their browsers, leading to a successful cross-site scripting attack.

Mitigation and Prevention

To address CVE-2021-20103, immediate action and long-term security practices are recommended.

Immediate Steps to Take

Users should update Machform to version 16 or later to mitigate the vulnerability and prevent exploitation. Additionally, avoid opening attachments from untrusted sources.

Long-Term Security Practices

Regularly update software to the latest versions, implement web application firewalls, conduct security audits, and educate users on safe browsing practices to enhance overall security posture.

Patching and Updates

Stay informed about security advisories and promptly apply patches released by the vendor to address known vulnerabilities and protect systems from exploitation.