CVE-2025-64345 Wasmtime provides unsound API access to a WebAssembly shared linear memory

What is CVE-2025-64345?

CVE-2025-64345 is a low-severity vulnerability in bytecodealliance wasmtime, published on 12 Nov 2025. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

Wasmtime is a runtime for WebAssembly. Prior to version 38.0.4, 37.0.3, 36.0.3, and 24.0.5, Wasmtime's Rust embedder API contains an unsound interaction where a WebAssembly shared linear memory could be viewed as a type which provides safe access to the host (Rust) to the contents of the linear memory. This is not sound for shared linear memories, which could be modified in parallel, and this could lead to a data race in the host. Patch releases have been issued for all supported versions of Wasmtime, notably: 24.0.5, 36.0.3, 37.0.3, and 38.0.4. These releases reject creation of shared memories via `Memory::new` and shared memories are now excluded from core dumps. As a workaround, eembeddings affected by this issue should use `SharedMemory::new` instead of `Memory::new` to create shared memories. Affected embeddings should also disable core dumps if they are unable to upgrade. Note that core dumps are disabled by default but the wasm threads proposal (and shared memory) is enabled by default.

Weakness: CWE-362

Which versions are affected by CVE-2025-64345?

9 open source packages ship an affected version, including wasmtime.

How do I fix CVE-2025-64345?

Upgrade wasmtime to a fixed version for your release line: 24.0.5, 36.0.3, 37.0.3 or 38.0.4.

Is CVE-2025-64345 being exploited?

There is no known exploitation of CVE-2025-64345 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2025-64345, GHSA-hc7m-r6v8-hg9q, JLSEC-2026-1350, RUSTSEC-2025-0118, UBUNTU-CVE-2025-64345.