CVE-2023-6393 is a vulnerability identified in the Red Hat build of Quarkus version 2.13.9.Final, specifically within the Quarkus Cache Runtime component. The issue arises when request processing involves a Uni object cached using the @CacheResult annotation. Normally, each request should process within its own context to ensure data isolation. However, due to this flaw, the cached Uni reuses the initial completion context instead of switching to the current request's context. This means that when a POST request is processed, it may inadvertently return a cached response that contains sensitive information from a previous user’s request. This behavior leads to unauthorized exposure of sensitive data to malicious actors who can craft requests to retrieve data not intended for them. The vulnerability affects confidentiality but does not impact data integrity or system availability. The CVSS v3.1 score is 5.3 (medium severity), reflecting that the attack vector is network-based, requires low privileges, and no user interaction, but has a high impact on confidentiality. There are no known exploits in the wild at the time of publication. The flaw is particularly relevant for applications using Quarkus for microservices or cloud-native deployments where caching is leveraged for performance optimization. Without proper mitigation, this vulnerability could lead to data leaks between users in multi-tenant or shared environments.

For European organizations, the primary impact of CVE-2023-6393 is the unauthorized disclosure of sensitive information, which can lead to data breaches and non-compliance with data protection regulations such as the GDPR. Exposure of personal data or confidential business information could result in reputational damage, regulatory fines, and loss of customer trust. Organizations relying on Red Hat Quarkus for critical applications, especially those handling personal or financial data, are at risk. The vulnerability could be exploited remotely over the network with low privileges, increasing the attack surface. Although the vulnerability does not affect system integrity or availability, the confidentiality breach alone is significant for sectors like finance, healthcare, and government services prevalent in Europe. The risk is heightened in multi-tenant cloud environments or SaaS platforms where cached responses might be shared across users. Consequently, European entities must assess their use of affected Quarkus versions and implement mitigations promptly to avoid potential data leaks.

To mitigate CVE-2023-6393, organizations should first apply any available patches or updates from Red Hat or the Quarkus project that address the caching context reuse issue. If patches are not immediately available, consider disabling caching for Uni objects annotated with @CacheResult in sensitive contexts or avoid caching POST request responses that may contain user-specific data. Implement strict access controls and monitoring around services using Quarkus caching to detect anomalous access patterns. Review application logic to ensure that cached data does not include sensitive information or that context switching is correctly handled per request. Employ network segmentation and firewall rules to limit exposure of vulnerable services to trusted networks only. Additionally, conduct thorough testing of caching behavior in staging environments to verify that context isolation is maintained. Finally, maintain an incident response plan to quickly address any suspected data exposure incidents related to this vulnerability.