CVE-2023-27495 : What You Need to Know

This CVE record highlights a vulnerability in the @fastify/csrf-protection plugin that could potentially lead to a bypass of CSRF protection under certain conditions.

Understanding CVE-2023-27495

This vulnerability impacts the @fastify/csrf-protection plugin, a tool designed to safeguard Fastify servers against Cross-Site Request Forgery (CSRF) attacks. The vulnerability allows for the bypass of CSRF protection when certain conditions are met, potentially exposing servers to exploitation by network and same-site attackers.

What is CVE-2023-27495?

The vulnerability in the @fastify/csrf-protection plugin allows attackers to bypass CSRF protection mechanisms by fixating a _csrf cookie in the victim's browser and forging CSRF tokens valid for the victim's session. This occurs when the optional userInfo parameter, designed to bind the CSRF token to the user, is missing or its value can be predicted for the target user account.

The Impact of CVE-2023-27495

The impact of this vulnerability is significant as it can potentially lead to unauthorized access and manipulation of user sessions, putting sensitive data at risk. Attackers could exploit this vulnerability to perform malicious actions on behalf of authenticated users.

Technical Details of CVE-2023-27495

This section covers the technical aspects of the CVE-2023-27495 vulnerability in the @fastify/csrf-protection plugin.

Vulnerability Description

The vulnerability arises due to the lack of proper validation and enforcement of the userInfo parameter in the @fastify/csrf-protection plugin, allowing attackers to bypass CSRF protection mechanisms.

Affected Systems and Versions

The @fastify/csrf-protection versions below 4.1.0 and versions between 5.0.0 and 6.3.0 are affected by this vulnerability. Users utilizing these versions are at risk and are advised to take immediate action.

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating the userInfo parameter to predict or manipulate CSRF tokens, thereby bypassing the CSRF protection mechanism and gaining unauthorized access to user sessions.

Mitigation and Prevention

Addressing CVE-2023-27495 requires immediate action to secure systems and prevent potential exploitation of the vulnerability.

Immediate Steps to Take

Users are strongly advised to upgrade to @fastify/csrf-protection versions 4.1.0 or higher, or versions 6.3.0 and above, where the vulnerability has been patched. Upgrading to these secure versions will help mitigate the risk of CSRF protection bypass.

Long-Term Security Practices

Incorporate best security practices such as implementing randomized, non-predictable values for the userInfo parameter for each user. This practice enhances security by making it harder for attackers to predict and manipulate CSRF tokens.

Patching and Updates

Regularly monitor for security updates and patches released by @fastify/csrf-protection and promptly apply them to ensure that systems are protected against known vulnerabilities and exploits. Regular updates are crucial to maintaining a secure environment and safeguarding against potential threats.