CVE-2021-21357 : Vulnerability Insights and Analysis

TYPO3.CMS before versions 8.7.40, 9.5.25, 10.4.14, 11.1.1 is vulnerable to a broken access control issue in the Form Framework due to improper input validation. Attackers can bypass restrictions and submit arbitrary data, potentially allowing malicious file uploads. A valid backend user account is required for exploitation.

Understanding CVE-2021-21357

This CVE pertains to a broken access control vulnerability in TYPO3.CMS, potentially enabling attackers to upload malicious files.

What is CVE-2021-21357?

In TYPO3.CMS versions prior to 8.7.40, 9.5.25, 10.4.14, and 11.1.1, a flaw in input validation allows attackers to bypass restrictions in the Form Framework. This opens the door for arbitrary file uploads, with the need for a valid backend user account.

The Impact of CVE-2021-21357

The impact of this vulnerability is rated as HIGH severity with an overall CVSS base score of 8.3. It poses a risk of compromising data integrity and availability.

Technical Details of CVE-2021-21357

This section delves into the vulnerability description, affected systems, and the exploitation mechanism.

Vulnerability Description

The vulnerability stems from improper input validation in TYPO3.CMS, enabling attackers to upload arbitrary files via the Form Designer backend module.

Affected Systems and Versions

TYPO3.CMS versions from 8.0.0 to 11.1.0 are affected, including versions 8.7.39, 9.5.24, 10.4.13, and 11.1.0.

Exploitation Mechanism

Exploiting this vulnerability requires a valid backend user account with access to the form module, allowing attackers to bypass predefined restrictions.

Mitigation and Prevention

To secure systems against CVE-2021-21357, immediate action and long-term security practices are crucial.

Immediate Steps to Take

It is recommended to update TYPO3.CMS to versions 8.7.40, 9.5.25, 10.4.14, or 11.1.1 to patch the access control issue.

Long-Term Security Practices

Implement strict input validation mechanisms, monitor file uploads diligently, and restrict access to sensitive modules to prevent such vulnerabilities.

Patching and Updates

Regularly apply security patches and updates released by TYPO3 to address any security loopholes and protect systems from potential threats.