wasmtime suffers a type‑confusion flaw where several Store APIs do not confirm that objects belong to the same Engine. An embedder that mixes objects from different Engines—via Instance::new, StructRefPre::new, or Tag::new—can cause trampoline signature mismatches that trigger out‑of‑bounds stack writes, garbage‑collector heap corruption, or abrupt panics. These memory corruptions could lead to arbitrary code execution or denial‑of‑service conditions within the host process that runs wasmtime. The description does not state a confirmed exploitation path, but the severity of the memory corruption is significant if the embedding application is compromised.

Bytecode Alliance’s wasmtime engine. The vulnerability affects wasmtime versions before 24.0.12, before 36.0.13 of 25.0.0, before 46.0.2 of 37.0.0, and before 47.0.3 of 47.0.0.

The CVSS score of 1.0 is low and no EPSS data is available, and the vulnerability is not listed in CISA’s KEV catalog. This suggests limited exploitation activity observed so far. However, exploitation requires ability to execute wasmtime code or influence its API calls, which is typically a local privilege or embedded‑system scenario. The attack vector is inferred to be local; an attacker who can control input to the embedding application would need to orchestrate Engine mixing to trigger the type confusion. Given the low public exploitation metrics, the immediate risk to externally exposed services appears modest, yet the impact of a successful exploitation would be severe due to memory corruption.