CVE-2024-22258 in Spring Authorization Server
Summary
by MITRE • 03/20/2024
Spring Authorization Server versions 1.0.0 - 1.0.5, 1.1.0 - 1.1.5, 1.2.0 - 1.2.2 and older unsupported versions are susceptible to a PKCE Downgrade Attack for Confidential Clients.
Specifically, an application is vulnerable when a Confidential Client uses PKCE for the Authorization Code Grant.
An application is not vulnerable when a Public Client uses PKCE for the Authorization Code Grant.
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Analysis
by VulDB Data Team • 12/06/2024
The vulnerability identified as CVE-2024-22258 represents a significant security weakness in Spring Authorization Server implementations that affects multiple version ranges including 1.0.0 through 1.0.5, 1.1.0 through 1.1.5, and 1.2.0 through 1.2.2 along with older unsupported versions. This flaw specifically targets the implementation of Proof Key for Code Exchange (PKCE) mechanisms for confidential clients within the OAuth 2.0 authorization framework. The security risk emerges from the server's inability to properly enforce PKCE requirements for confidential clients, creating a potential attack vector that could be exploited by malicious actors seeking to compromise authorization flows. The vulnerability is particularly concerning because it undermines the core security benefits that PKCE provides in preventing authorization code interception attacks.
The technical flaw manifests in the authorization server's handling of PKCE parameters when confidential clients utilize the authorization code grant flow. In a properly implemented system, PKCE should be mandatory for confidential clients to ensure that authorization codes cannot be intercepted and reused by attackers. However, this vulnerability allows for a downgrade attack where the server fails to validate or enforce PKCE requirements for confidential clients, effectively weakening the security posture of applications relying on these server implementations. The flaw specifically impacts the authorization code grant type where confidential clients should be required to provide PKCE parameters, but the server accepts requests without proper validation. This represents a deviation from the OAuth 2.0 security best practices and creates a scenario where attackers can potentially bypass the security controls that PKCE is designed to provide.
The operational impact of this vulnerability extends beyond simple authentication bypasses to potentially enable more sophisticated attacks including authorization code interception and replay attacks. When confidential clients are not properly required to implement PKCE, malicious actors can exploit the weakened security controls to intercept authorization codes and potentially gain unauthorized access to protected resources. The vulnerability affects applications that rely on Spring Authorization Server for managing OAuth 2.0 flows, particularly those handling sensitive data or privileged access. The downgrade attack capability means that even if an application correctly implements PKCE for public clients, the server's failure to enforce PKCE for confidential clients creates a security gap that can be exploited to compromise the entire authorization flow. This vulnerability is particularly dangerous because it affects the fundamental security mechanisms that protect OAuth 2.0 implementations from common attack patterns.
Organizations using affected Spring Authorization Server versions should prioritize immediate remediation through patching to version 1.2.3 or later where this vulnerability has been addressed. The mitigation strategy should include comprehensive testing of all confidential client implementations to ensure proper PKCE enforcement and validation. Security teams should also implement monitoring for unauthorized access attempts that might indicate exploitation of this vulnerability. The recommended approach involves updating the server configuration to enforce mandatory PKCE for all confidential clients and implementing proper validation mechanisms that verify PKCE parameters during authorization code exchanges. Additionally, organizations should review their existing authorization flows to identify any potential impact from the downgrade attack scenario and implement compensating controls where necessary. This vulnerability aligns with CWE-310 (Cryptographic Issues) and may be categorized under ATT&CK technique T1566 (Phishing) when exploited in conjunction with other attack vectors, though the primary threat is the weakening of authorization security controls through improper PKCE enforcement.