cvedb.io
CVE-2021-39216
MEDIUM · CVSS 6.3
EPSS exploitation probability: 0%
Published 2021-09-17T20:15:07.703 · Last modified 2026-06-17T04:03:19.810

Summary

Wasmtime is an open source runtime for WebAssembly & WASI. In Wasmtime from version 0.19.0 and before version 0.30.0 there was a use-after-free bug when passing `externref`s from the host to guest Wasm content. To trigger the bug, you have to explicitly pass multiple `externref`s from the host to a Wasm instance at the same time, either by passing multiple `externref`s as arguments from host code to a Wasm function, or returning multiple `externref`s to Wasm from a multi-value return function defined in the host. If you do not have host code that matches one of these shapes, then you are not impacted. If Wasmtime's `VMExternRefActivationsTable` became filled to capacity after passing the first `externref` in, then passing in the second `externref` could trigger a garbage collection. Howeve

Affected products

bytecodealliance — wasmtime

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.