CVE-2026-34983

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.

• CWE-416

• https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2Mitigation, Vendor Advisory
• https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2Mitigation, Vendor Advisory

Published

Apr 9, 2026

Last Modified

Jun 17, 2026

Status

Analyzed

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