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 uses a Uni object cached via the @CacheResult annotation. Normally, each request should operate 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 leads to a scenario where a POST request can inadvertently receive a cached response containing sensitive information from a previous request belonging to another user. The vulnerability exposes sensitive data, violating confidentiality, but does not affect data integrity or system availability. The CVSS 3.1 score is 5.3 (medium), reflecting network attack vector, high attack complexity, low privileges required, no user interaction, and high confidentiality impact. No known exploits have been reported in the wild, but the flaw could be leveraged by attackers with network access to extract sensitive data from vulnerable applications. The root cause is improper context management in the caching mechanism, which should isolate cached data per user or request context. This vulnerability is particularly relevant for applications handling sensitive or personal data, such as financial, healthcare, or governmental services built on Quarkus. Since Red Hat Quarkus is widely used in enterprise Java applications, the flaw poses a risk to organizations relying on this framework for secure data processing.

For European organizations, the primary impact of CVE-2023-6393 is the unauthorized exposure of sensitive information due to improper caching context isolation. This can lead to data breaches involving personal data, intellectual property, or confidential business information, potentially violating GDPR and other data protection regulations. The exposure of sensitive data can damage organizational reputation, incur regulatory fines, and result in loss of customer trust. Since the vulnerability affects the confidentiality of data without impacting integrity or availability, the main concern is data leakage rather than service disruption. Organizations running web applications or microservices using the affected Quarkus version are at risk, especially those processing POST requests with sensitive payloads. The medium CVSS score indicates moderate risk, but the actual impact depends on the nature of cached data and application context. Attackers with network access and low privileges can exploit this flaw without user interaction, increasing the threat surface. European sectors such as finance, healthcare, public administration, and critical infrastructure that use Red Hat Quarkus could face significant consequences if exploited.

1. Monitor Red Hat and Quarkus official advisories for patches addressing CVE-2023-6393 and apply updates promptly once available. 2. Until a patch is released, review application caching strategies to avoid caching sensitive data in contexts that may be shared across users or requests. 3. Implement strict cache context isolation by ensuring that cached Uni objects do not reuse completion contexts containing sensitive information. 4. Conduct thorough code audits focusing on usage of @CacheResult and Uni caching to identify and remediate unsafe caching patterns. 5. Employ runtime application self-protection (RASP) or web application firewalls (WAF) to monitor and block suspicious POST requests that might exploit this flaw. 6. Enhance logging and monitoring to detect anomalous access patterns or unexpected data exposures related to cached responses. 7. Educate developers on secure caching practices within reactive programming frameworks like Quarkus to prevent similar issues. 8. Consider architectural changes to separate sensitive data processing from caching layers or use encryption for cached data where feasible.