A memory leak vulnerability was discovered in SmallRye Fault Tolerance core. When a programmatic Guard, TypedGuard, or FaultTolerance is invoked through the ApplyGuard or the deprecated ApplyFaultTolerance annotations, the library retains one DelegatingMeteredOperation and one MetricsCollector instance per invocation for the lifetime of the singleton guard.

The root cause is that these objects are never released, causing the heap to grow linearly with the number of calls. An unauthenticated remote attacker can exploit this by sending a high volume of requests to a vulnerable endpoint, leading to increased garbage collection pressure, significant performance degradation, and an eventual OutOfMemoryError OOM condition. This impact occurs regardless of whether a description is set for the guard.