CVE-2024-21664 in jwx
Summary
by MITRE • 01/09/2024
jwx is a Go module implementing various JWx (JWA/JWE/JWK/JWS/JWT, otherwise known as JOSE) technologies. Calling `jws.Parse` with a JSON serialized payload where the `signature` field is present while `protected` is absent can lead to a nil pointer dereference. The vulnerability can be used to crash/DOS a system doing JWS verification. This vulnerability has been patched in version 2.0.19.
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Analysis
by VulDB Data Team • 01/27/2024
The vulnerability identified as CVE-2024-21664 affects the jwx Go module, a widely used library implementing JOSE (JSON Object Signing and Encryption) standards including JWA, JWE, JWK, JWS, and JWT technologies. This security flaw specifically targets the JWS (JSON Web Signature) parsing functionality, creating a critical condition that can be exploited to cause system crashes or denial of service attacks. The vulnerability stems from improper handling of JSON serialized payloads during the parsing process, where the library fails to adequately validate the structure of incoming signature data before attempting to process it.
The technical flaw manifests when the jws.Parse function encounters a JSON payload containing a signature field but lacking a protected field. This scenario creates a nil pointer dereference condition within the library's internal processing logic, as the code attempts to access memory locations that have not been properly initialized or allocated. The absence of proper input validation allows malicious actors to craft specifically formatted JSON payloads that trigger this memory access violation, leading to application crashes and system instability. This type of vulnerability falls under CWE-476, which specifically addresses NULL pointer dereferences, and represents a classic example of improper input validation in security-critical code paths.
The operational impact of this vulnerability extends beyond simple system crashes, as it can be weaponized to create denial of service conditions that affect applications relying on jwx for authentication and authorization processes. Systems that process untrusted JWS tokens, such as web applications, API gateways, and authentication services, become vulnerable to attacks that can render them unavailable to legitimate users. The vulnerability is particularly concerning because it can be triggered through normal parsing operations without requiring special privileges or complex exploitation techniques, making it accessible to a wide range of threat actors. This aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how seemingly benign input processing can become a vector for system compromise.
Organizations utilizing the jwx library in their security infrastructure must prioritize immediate remediation through the upgrade to version 2.0.19, which contains the necessary patches to address this nil pointer dereference vulnerability. Security teams should conduct comprehensive vulnerability assessments to identify all systems and applications that depend on affected versions of the library, ensuring that the patch is applied consistently across the entire infrastructure. Additionally, implementing proper input validation and sanitization measures at application boundaries can provide additional defense-in-depth protection against similar vulnerabilities. The fix implemented in version 2.0.19 demonstrates the importance of robust error handling and input validation in cryptographic libraries, where improper handling of edge cases can lead to critical system failures. Organizations should also consider monitoring for potential exploitation attempts through network intrusion detection systems and application logs to identify any attempts to leverage this vulnerability in active attacks.