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CVE-2021-39218
MEDIUM · CVSS 6.3
EPSS exploitation probability: 0%
Published 2021-09-17T21:15:07.417 · Last modified 2026-06-17T04:03:20.090

Summary

Wasmtime is an open source runtime for WebAssembly & WASI. In Wasmtime from version 0.26.0 and before version 0.30.0 is affected by a memory unsoundness vulnerability. There was an invalid free and out-of-bounds read and write bug when running Wasm that uses `externref`s in Wasmtime. To trigger this bug, Wasmtime needs to be running Wasm that uses `externref`s, the host creates non-null `externrefs`, Wasmtime performs a garbage collection (GC), and there has to be a Wasm frame on the stack that is at a GC safepoint where there are no live references at this safepoint, and there is a safepoint with live references earlier in this frame's function. Under this scenario, Wasmtime would incorrectly use the GC stack map for the safepoint from earlier in the function instead of the empty safepoin

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.