CVE-2025-3631 is a use-after-free vulnerability (CWE-416) identified in IBM MQ versions 9.3.2.0 CD, 9.4.0.0, and 9.4.0.0 LTS. IBM MQ is a widely used message queuing middleware that facilitates communication between distributed applications by sending and receiving messages asynchronously. The vulnerability arises when an IBM MQ client connects to an MQ Queue Manager, causing a segmentation fault (SIGSEGV) in the AMQRMPPA channel process. This process termination is due to improper handling of memory, specifically a use-after-free condition, where the software attempts to access memory that has already been freed. The consequence is a denial of service (DoS) condition, as the channel process responsible for managing communication is terminated unexpectedly. The CVSS v3.1 base score is 6.5, indicating a medium severity level. The vector string (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) shows that the vulnerability is remotely exploitable over the network with low attack complexity, requires low privileges (authenticated user), no user interaction, and impacts availability only, without affecting confidentiality or integrity. No known exploits are currently reported in the wild, and no patches are linked yet, suggesting that remediation may require vendor updates or configuration changes once available. The vulnerability does not allow for code execution or data compromise but can disrupt critical messaging infrastructure, potentially impacting business continuity.

For European organizations, the impact of CVE-2025-3631 can be significant, especially for enterprises relying heavily on IBM MQ for mission-critical messaging and integration services. The forced termination of the AMQRMPPA channel process can lead to service interruptions, message loss, and delays in communication between distributed systems. This can affect financial institutions, manufacturing, telecommunications, and public sector entities that depend on reliable message queuing for operational workflows. The denial of service could disrupt automated processes, cause cascading failures in dependent applications, and increase operational costs due to downtime and recovery efforts. Although the vulnerability does not compromise data confidentiality or integrity, the availability impact alone can lead to regulatory compliance issues under frameworks like GDPR if service disruptions affect personal data processing or availability commitments. The requirement for authenticated access reduces the risk from external attackers but raises concerns about insider threats or compromised credentials within organizations.

To mitigate CVE-2025-3631, European organizations should: 1) Immediately review and restrict access controls to IBM MQ clients and Queue Managers, ensuring that only trusted and authenticated users can connect. 2) Monitor MQ channel processes for abnormal terminations or crashes, implementing alerting mechanisms to detect potential exploitation attempts early. 3) Apply vendor-provided patches or updates as soon as they become available, prioritizing affected IBM MQ versions 9.3.2.0 CD, 9.4.0.0, and 9.4.0.0 LTS. 4) Consider deploying network segmentation and firewall rules to limit exposure of MQ services to only necessary internal systems. 5) Conduct regular security audits and penetration testing focused on MQ infrastructure to identify and remediate potential weaknesses. 6) Implement robust credential management and multi-factor authentication to reduce the risk of unauthorized access. 7) Prepare incident response plans specifically addressing MQ service disruptions to minimize downtime and data loss in case of exploitation.