CVE-2021-41258 : Security Advisory and Response
Discover how CVE-2021-41258 impacted Kirby CMS versions >= 3.5.0, < 3.5.8 by enabling cross-site scripting (XSS) attacks. Learn about the severity, affected systems, and mitigation steps.
Kirby is an open-source file structured CMS. The vulnerability in Kirby versions >= 3.5.0 and < 3.5.8 allowed for cross-site scripting (XSS) attacks through the image block functionality.
Understanding CVE-2021-41258
Kirby's vulnerability stemmed from a lack of proper HTML character escaping in the default image block snippet, enabling attackers to inject malicious HTML code.
What is CVE-2021-41258?
The issue in affected Kirby versions allowed authenticated Panel users to insert malicious HTML in the image block fields, leading to XSS attacks on site visitors.
The Impact of CVE-2021-41258
The vulnerability's CVSS score of 7.3 marked it as a high-severity issue, with significant impacts on confidentiality and integrity, requiring low privileges for exploitation.
Technical Details of CVE-2021-41258
The technical details reveal how the XSS vulnerability affected Kirby's image block functionality.
Vulnerability Description
The XSS flaw in Kirby versions >= 3.5.0 and < 3.5.8 enabled the insertion of malicious HTML code in image block fields, affecting site visitors and logged-in users.
Affected Systems and Versions
- Product: Kirby
- Vendor: getkirby
- Vulnerable Versions: >= 3.5.0, < 3.5.8
Exploitation Mechanism
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: Low
- User Interaction: Required
- Scope: Unchanged
Mitigation and Prevention
To protect systems from CVE-2021-41258, immediate actions and long-term security practices are crucial.
Immediate Steps to Take
- Upgrade to Kirby version 3.5.8 or later to patch the XSS vulnerability.
Long-Term Security Practices
- Regularly update CMS and plugins to mitigate potential security risks.
- Implement input validation and proper output encoding to prevent XSS attacks.
- Conduct security audits and penetration testing to identify vulnerabilities.
- Educate users on safe practices to enhance overall security.
Patching and Updates
Ensure timely installation of security patches and updates to safeguard against known vulnerabilities.