CVE-2026-34983

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

Published: Apr 9, 2026Updated: Apr 15, 2026 Sources: CVE List NVDCWE-416

5.0MEDIUM

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:LAttack Vector

Local

AC:LAttack Complexity

Low

PR:LPrivileges Required

Low

UI:RUser Interaction

Required

Scope

S:UScope

Unchanged

Impact

C:NConfidentiality

None

I:NIntegrity

None

A:HAvailability

High

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Weaknesses

CWE-416

Affected Products

bytecodealliance

oss-project

wasmtimeLibraryLibrary

OSS Libraries / generic-library

Exploitability

Official Patch Available

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques

Initial Access

Privilege Escalation

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References

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

github.com

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