CVE-2012-6426 in LemonLDAP::NG
Summary
by MITRE
LemonLDAP::NG before 1.2.3 does not use the signature-verification capability of the Lasso library, which allows remote attackers to bypass intended access-control restrictions via crafted SAML data.
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Analysis
by VulDB Data Team • 05/28/2025
The vulnerability identified as CVE-2012-6426 affects LemonLDAP::NG versions prior to 1.2.3, representing a critical security flaw in the SAML authentication implementation. This issue stems from the application's failure to leverage the signature-verification capabilities inherent in the Lasso library, which is a core component for handling SAML assertions in the LemonLDAP::NG framework. The weakness creates a significant bypass opportunity for remote attackers who can manipulate SAML data to gain unauthorized access to protected resources.
The technical flaw resides in the improper handling of SAML assertions within the authentication process, specifically the absence of cryptographic signature validation. When SAML assertions are received, the system should verify the digital signatures to ensure the integrity and authenticity of the authentication data. However, LemonLDAP::NG versions before 1.2.3 fail to perform this crucial verification step, allowing attackers to craft malicious SAML data that appears legitimate to the system. This vulnerability maps directly to CWE-347, which addresses the lack of proper cryptographic verification mechanisms, and aligns with ATT&CK technique T1566.001 for credential harvesting through spearphishing with links.
The operational impact of this vulnerability is substantial as it enables attackers to bypass authentication controls entirely. Remote adversaries can construct forged SAML assertions that contain false identity claims or elevated privileges, potentially gaining access to systems, applications, or data that should be restricted. This weakness is particularly dangerous in enterprise environments where SAML is commonly used for single sign-on implementations, as it could allow unauthorized users to access sensitive corporate resources, customer data, or internal systems without proper authentication. The vulnerability affects the integrity and authenticity guarantees that SAML assertions are designed to provide, undermining the fundamental security model of the authentication system.
Organizations utilizing affected LemonLDAP::NG versions should immediately upgrade to version 1.2.3 or later to remediate this vulnerability. The patch addresses the core issue by implementing proper signature verification using the Lasso library's built-in capabilities. Additional mitigations include implementing network-level controls to restrict access to SAML endpoints, monitoring authentication logs for suspicious activities, and ensuring proper configuration of SAML trust relationships. Security teams should also consider implementing additional layers of authentication and authorization controls as defensive measures. The vulnerability demonstrates the critical importance of cryptographic verification in identity and access management systems, as highlighted in industry standards such as NIST SP 800-63B for digital identity management and ISO/IEC 27017 for cloud security controls.