CVE-2025-36005 is a medium severity vulnerability identified in multiple versions of the IBM MQ Operator, including LTS 2.0.0 through 2.0.29, CD versions 3.0.0 to 3.6.0, and SC2 versions 3.2.0 through 3.2.13. The vulnerability arises from improper certificate validation (CWE-295) in the Internet Pass-Thru component of the MQ Operator. Specifically, the flaw allows a malicious user to exploit the proxy mechanism that handles TLS session connections to the same hostname and port. Due to inadequate validation of TLS certificates, an attacker can potentially intercept or obtain sensitive information from another TLS session proxied through the same hostname and port. This vulnerability does not require user interaction or privileges and can be exploited remotely over the network. The CVSS v3.1 score is 5.9, reflecting a medium severity with high impact on confidentiality but no impact on integrity or availability. The attack complexity is high, meaning exploitation requires specific conditions or skills, and no known exploits are currently reported in the wild. The vulnerability affects the confidentiality of data transmitted over TLS sessions managed by the IBM MQ Operator, potentially exposing sensitive information such as credentials, messages, or configuration data. The issue stems from a failure to properly validate certificates, which is critical in ensuring secure TLS connections and preventing man-in-the-middle or session hijacking attacks within the MQ Operator's proxying functionality.

For European organizations using IBM MQ Operator in their messaging infrastructure, this vulnerability poses a risk of sensitive data exposure during TLS session proxying. IBM MQ is widely used in enterprise environments for reliable message queuing and integration, often handling critical business data and inter-application communication. Exposure of TLS session data could lead to leakage of confidential information, undermining data privacy and compliance with regulations such as GDPR. While the vulnerability does not allow direct code execution or service disruption, the confidentiality breach could facilitate further attacks or data exfiltration. Organizations in sectors such as finance, manufacturing, telecommunications, and government, which rely heavily on IBM MQ for secure messaging, may be particularly impacted. The medium severity and high attack complexity suggest that exploitation is not trivial but feasible by skilled attackers with network access. Given the cross-border nature of many European enterprises and their interconnected systems, the vulnerability could have cascading effects if exploited in supply chain or partner communications.

To mitigate this vulnerability, European organizations should prioritize updating IBM MQ Operator to versions beyond those affected, as IBM is expected to release patches addressing the improper certificate validation. In the absence of immediate patches, organizations should implement strict network segmentation and access controls to limit exposure of the MQ Operator's proxy endpoints to trusted networks and users only. Enforcing mutual TLS authentication and validating certificates at the network perimeter can reduce the risk of man-in-the-middle attacks. Monitoring network traffic for anomalous TLS session behaviors and proxy usage patterns can help detect potential exploitation attempts. Additionally, reviewing and hardening TLS configurations, including disabling legacy or weak cipher suites and ensuring proper certificate chain validation, will strengthen defenses. Organizations should also audit their MQ Operator deployments for exposure to untrusted networks and consider deploying additional application-layer gateways or intrusion detection systems to monitor MQ traffic. Finally, maintaining an incident response plan that includes this vulnerability scenario will improve readiness in case of exploitation.