CVE-2025-12466 in Simple OAuth & OpenID Connect
Summary
by MITRE • 10/30/2025
Authentication Bypass Using an Alternate Path or Channel vulnerability in Drupal Simple OAuth (OAuth2) & OpenID Connect allows Authentication Bypass.This issue affects Simple OAuth (OAuth2) & OpenID Connect: from 6.0.0 before 6.0.7.
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Analysis
by VulDB Data Team • 11/02/2025
The vulnerability identified as CVE-2025-12466 represents a critical authentication bypass flaw within the Drupal Simple OAuth module, specifically impacting versions 6.0.0 through 6.0.6. This issue resides in the OAuth2 and OpenID Connect implementations that form the foundation of modern web application authentication systems. The vulnerability stems from improper validation mechanisms that permit attackers to circumvent the standard authentication flow by utilizing alternative access paths or channels. Such flaws are particularly dangerous as they undermine the fundamental security assumptions of the authentication system, allowing unauthorized access to protected resources and user data.
The technical root cause of this vulnerability manifests in the module's insufficient validation of authentication tokens and session states during the OAuth2 and OpenID Connect authorization processes. Attackers can exploit this weakness by crafting specific requests that bypass the standard authentication checks while still gaining access to protected resources. The flaw operates at the application layer, specifically within the authentication middleware that handles token validation and user session management. This type of vulnerability is classified as CWE-287 - Improper Authentication, which directly aligns with the ATT&CK framework's T1078 - Valid Accounts technique, as it allows adversaries to gain access through legitimate authentication mechanisms without proper authorization. The vulnerability's impact extends beyond simple access control as it can enable further exploitation through privilege escalation or data exfiltration attacks.
The operational impact of this authentication bypass vulnerability is severe and multifaceted across Drupal implementations. Organizations utilizing affected versions of the Simple OAuth module face potential unauthorized access to user accounts, sensitive data exposure, and possible system compromise. The vulnerability affects not only the authentication process itself but also the trust model that OAuth2 and OpenID Connect protocols are designed to establish. Attackers could potentially impersonate legitimate users, access administrative functions, or perform unauthorized transactions depending on the application's configuration. This type of flaw particularly impacts web applications that rely heavily on third-party authentication services, as it undermines the security guarantees provided by the OAuth2 framework. The vulnerability's exploitation requires minimal technical expertise and can be automated, making it particularly dangerous for widespread deployment.
Mitigation strategies for CVE-2025-12466 focus primarily on immediate version upgrades to 6.0.7 or later, which contain the necessary patches addressing the authentication bypass mechanism. Organizations should conduct thorough security assessments of their Drupal installations to identify all affected systems and ensure complete remediation. Network-level mitigations such as implementing additional authentication layers, rate limiting, and monitoring for anomalous authentication patterns can provide temporary protection while patches are deployed. Security teams should also review and audit existing authentication configurations to ensure proper implementation of multi-factor authentication and session management controls. The remediation process must include comprehensive testing to verify that the patch does not introduce regressions in existing functionality. Additionally, organizations should implement continuous monitoring solutions to detect potential exploitation attempts and maintain up-to-date security intelligence feeds to stay informed about similar vulnerabilities in related components. Regular security assessments and vulnerability scanning should be integrated into the development lifecycle to prevent similar issues from emerging in future releases.