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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.

PUBLISHED Reserved 2026-03-31 | Published 2026-04-09 | Updated 2026-04-13 | Assigner GitHub_M




LOW: 1.0CVSS:4.0/AV:P/AC:H/AT:P/PR:H/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

Problem types

CWE-416: Use After Free

Product status

>= 43.0.0, < 43.0.1
affected

References

github.com/...smtime/security/advisories/GHSA-hfr4-7c6c-48w2 exploit

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

cve.org (CVE-2026-34983)

nvd.nist.gov (CVE-2026-34983)

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