MEDIUM 5.0
PYSEC-2026-151
Details
Wasmtime is a runtime for WebAssembly. In 43.0.0, cloning a wasmtime::Linker is unsound and can result in use-after-free bugs. This bug is not controllable by guest Wasm programs. It can only be triggered by a specific sequence of embedder API calls made by the host. Specifically, the following steps must occur to trigger the bug clone a wasmtime::Linker, drop the original linker instance, use the new, cloned linker instance, resulting in a use-after-free. This vulnerability is fixed in 43.0.1.
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Affected packages
PyPI / wasmtime
Introduced in:
0 No fixed version published yet for wasmtime (pip). Pin to a known-safe version or switch to an alternative.