CVE-2023-49594 identifies an information disclosure vulnerability classified under CWE-201 (Information Exposure Through Sent Data) in the instipod DuoUniversalKeycloakAuthenticator plugin version 1.0.7. This plugin integrates Duo Universal 2FA with Keycloak, a widely used open-source identity and access management solution. The vulnerability exists in the challenge functionality during the authentication process. When a user attempts to log in using this plugin, a specially crafted HTTP request can trigger the flaw, causing the system to leak sensitive information. The leaked data could include authentication challenge details or other sensitive tokens that should remain confidential. The vulnerability requires an attacker to have high privileges (PR:H) and user interaction (UI:R), meaning the attacker must be authenticated and the user must participate in the login process. The attack vector is network-based (AV:N), allowing remote exploitation. The vulnerability does not affect integrity or availability, only confidentiality, resulting in a CVSS v3.1 score of 4.5 (medium severity). No patches are currently listed, and no known exploits have been reported in the wild. The flaw could be leveraged by attackers to gain intelligence on authentication mechanisms or user credentials, potentially facilitating further targeted attacks or lateral movement within networks using Keycloak with this plugin.

For European organizations, the primary impact is the exposure of sensitive authentication-related information, which can compromise user privacy and potentially aid attackers in crafting more effective phishing or credential-stuffing attacks. Organizations relying on Keycloak with the instipod DuoUniversalKeycloakAuthenticator plugin version 1.0.7 for multi-factor authentication are at risk. This could affect sectors with stringent security requirements such as finance, healthcare, government, and critical infrastructure. The confidentiality breach may lead to regulatory compliance issues under GDPR due to unauthorized disclosure of personal data. Although the vulnerability does not directly impact system integrity or availability, the information disclosed could be used in subsequent attacks that might cause broader harm. The requirement for high privileges and user interaction limits the attack scope but does not eliminate risk, especially in environments with many privileged users or exposed authentication portals.

1. Monitor for updates or patches from instipod for the DuoUniversalKeycloakAuthenticator plugin and apply them promptly once available. 2. Restrict access to Keycloak authentication endpoints to trusted networks and users to reduce exposure to crafted HTTP requests. 3. Implement strict network segmentation and access controls around identity management infrastructure. 4. Conduct regular audits of authentication logs to detect unusual or suspicious login attempts that could indicate exploitation attempts. 5. Educate privileged users about the risk of interacting with suspicious authentication prompts or links. 6. Consider deploying Web Application Firewalls (WAFs) with rules to detect and block anomalous HTTP requests targeting the authentication challenge endpoints. 7. Evaluate alternative 2FA plugins or solutions if patching is delayed, to reduce exposure. 8. Ensure that all components of the authentication stack are kept up to date and hardened according to best practices.