CVE-2023-48223 : Security Advisory and Response

This article provides detailed information on CVE-2023-48223, a vulnerability in the fast-jwt library affecting versions prior to 3.3.2.

Understanding CVE-2023-48223

This section covers what CVE-2023-48223 is, its impact, technical details, and mitigation strategies.

What is CVE-2023-48223?

CVE-2023-48223 is an improper input validation vulnerability in the fast-jwt library, allowing attackers to exploit JWT algorithm confusion for public key types.

The Impact of CVE-2023-48223

The vulnerability can be exploited by crafting a malicious JWT token using the HS256 algorithm and the victim application's public RSA key, enabling attackers to sign arbitrary payloads that will be accepted by the verifier.

Technical Details of CVE-2023-48223

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

Vulnerability Description

The 'publicKeyPemMatcher' in 'fast-jwt/src/crypto.js' fails to match all common PEM formats for public keys, leading to algorithm confusion. A patch is available in version 3.3.2.

Affected Systems and Versions

The vulnerability affects versions of fast-jwt library prior to 3.3.2.

Exploitation Mechanism

Attackers can exploit the vulnerability by crafting a malicious JWT token with the HS256 algorithm and the victim application's public RSA key.

Mitigation and Prevention

Learn how to mitigate the CVE-2023-48223 vulnerability and secure your systems.

Immediate Steps to Take

Update to version 3.3.2 of the fast-jwt library. Additionally, modify line 29 of

blob/master/src/crypto.js

to include a regular expression.

Long-Term Security Practices

Implement security best practices such as verifying algorithms explicitly and regularly updating libraries.

Patching and Updates

Stay informed about security updates for the fast-jwt library and apply patches promptly.