Wasmtime versions >=46.0.0 <46.0.2 and >=47.0.0 <47.0.3 contain a race condition (CWE-362) in bulk operations involving fuel and epoch preemption checks. When an embedder mutates a Store during Store::epoch_deadline_callback or continues using a Store after cancellation or traps, invalid intermediate states can occur. Specific issues include cancelled non-nullable table growth leaving null elements, linear-memory growth invalidating retained raw pointers during memory.copy, and callback-triggered garbage collection invalidating GC pointers during array.copy. These conditions may cause crashes, invalid memory access, or GC heap corruption. Embeddings that only access host data or discard Stores after timeout are not vulnerable. The issue is resolved in versions 46.0.2 and 47.0.3.

The vulnerability can cause application crashes, invalid memory accesses, or corruption of the garbage collector heap due to race conditions during bulk operations in Wasmtime. This may affect the stability and reliability of applications embedding Wasmtime under certain concurrency conditions. However, embeddings that do not mutate Stores during callbacks or discard Stores after timeout are not impacted. The CVSS score is low, indicating limited severity.

This vulnerability is fixed in Wasmtime versions 46.0.2 and 47.0.3. Users should upgrade to these or later versions to remediate the issue. Embeddings that only access host data in Store<T> or discard Stores after timeout or epoch deadline are not affected and require no additional action.