CVE-2021-21355 : What You Need to Know
Learn about CVE-2021-21355, a high-severity vulnerability in TYPO3.CMS allowing unrestricted file uploads. Understand the impact, affected versions, and mitigation steps.
A security vulnerability has been identified in TYPO3.CMS versions before 8.7.40, 9.5.25, 10.4.14, and 11.1.1. This vulnerability allows attackers to upload arbitrary data with arbitrary file extensions without proper validation, potentially leading to unauthorized access or disclosure of sensitive information.
Understanding CVE-2021-21355
This CVE identifies an unrestricted file upload vulnerability in the TYPO3 Form Framework, enabling attackers to upload malicious files onto the affected system.
What is CVE-2021-21355?
TYPO3.CMS, an open-source PHP-based web content management system, is affected by a file upload vulnerability that can be exploited by attackers to upload arbitrary data with arbitrary file extensions. This could lead to unauthorized access and disclosure of sensitive information.
The Impact of CVE-2021-21355
The impact of this vulnerability is rated as high severity, with a CVSS base score of 8.6. It poses a threat to the integrity of the system, allowing attackers to upload malicious files without proper validation, potentially leading to data compromise.
Technical Details of CVE-2021-21355
This section outlines the specific technical details of the CVE.
Vulnerability Description
Due to a lack of validation on file extensions, an attacker can upload arbitrary data with arbitrary file extensions. The lack of proper file type verification can lead to unauthorized access and file disclosure.
Affected Systems and Versions
The vulnerability affects TYPO3.CMS versions before 8.7.40, 9.5.25, 10.4.14, and 11.1.1.
Exploitation Mechanism
Attackers can exploit this vulnerability by uploading files with arbitrary extensions onto the affected TYPO3.CMS system without proper validation.
Mitigation and Prevention
Protecting your system from CVE-2021-21355 requires immediate action and long-term security practices.
Immediate Steps to Take
Update TYPO3.CMS to versions 8.7.40, 9.5.25, 10.4.14, or 11.1.1 to mitigate the vulnerability. Additionally, review and restrict file upload permissions.
Long-Term Security Practices
Implement robust file upload validation mechanisms, perform regular security audits on your system, and educate users on safe file upload practices.
Patching and Updates
Stay informed about security advisories from TYPO3 and apply patches promptly to protect your system from known vulnerabilities.