Wasmtime has a use-after-free bug after cloning `wasmtime::Linker`_CVE-2026-34983

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LOW

CVSS:4.0/AV:P/AC:H/AT:P/PR:H/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

Description

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.

Basic Information

ID CVE-2026-34983

Source GitHub_M

Published Apr 9, 2026 at 18:47

Affected Product

Vendor bytecodealliance

Product wasmtime

Version >= 43.0.0, < 43.0.1

Affected Versions bytecodealliance wasmtime >= 43.0.0, < 43.0.1

CWE Classification

CWE-416

References

github.com /bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2

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    "published": "2026-04-09T18:47:26.575Z",
    "modified": "2026-04-09T18:47:26.575Z",
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