CVE-2026-74241 is a vulnerability in Red Hat Quay's external LDAP authentication mechanism. When an LDAP referral is returned during authentication, the system fails to properly escape the username input, allowing an attacker to inject LDAP filter metacharacters. This improper neutralization of special elements (CWE-90) enables user-existence oracle attacks against the referral DN and may affect password binding selection in multi-domain Active Directory setups. The vulnerability has a CVSS 3.1 base score of 4.8 (medium severity) with network attack vector, high attack complexity, no privileges required, and no user interaction. Red Hat has not released a patch or official fix yet, citing lack of suitable mitigation options that meet their criteria for ease of use, applicability, and stability.

The vulnerability allows an attacker to perform user-existence oracle attacks by injecting LDAP filter metacharacters during referral processing in LDAP authentication. This can reveal information about valid users in the directory. Additionally, it may influence which Directory Name is used for password binding in multi-domain Active Directory environments. However, direct authentication bypass is not possible, and directory enumeration is limited. The overall confidentiality and integrity impact is low, with no availability impact.

Currently, there is no official fix or patch available from Red Hat that meets their criteria for deployment and stability. Red Hat advises monitoring their advisory for updates. No specific mitigations are provided, and users should be aware of the potential for user-existence oracle attacks. Customers with Red Hat Technical Account Managers (TAM) can consult directly for guidance. It is recommended to follow Red Hat's official channels for any future patches or mitigations.