Wasmtime panics when lifting `flags` component value_CVE-2026-34943

5.6 / 10

MEDIUM

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

Description

Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime contains a possible panic which can happen when a flags-typed component model value is lifted with the Val type. If bits are set outside of the set of flags the component model specifies that these bits should be ignored but Wasmtime will panic when this value is lifted. This panic only affects wasmtime's implementation of lifting into Val, not when using the flags! macro. This additionally only affects flags-typed values which are part of a WIT interface. This has the risk of being a guest-controlled panic within the host which Wasmtime considers a DoS vector. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.

Basic Information

ID CVE-2026-34943

Source GitHub_M

Published Apr 9, 2026 at 18:36

Affected Product

Vendor bytecodealliance

Product wasmtime

Version < 24.0.7

Affected Versions bytecodealliance wasmtime < 24.0.7
bytecodealliance wasmtime >= 25.0.0, < 36.0.7
bytecodealliance wasmtime >= 37.0.0, < 42.0.2
bytecodealliance wasmtime >= 43.0.0, < 44.0.1

CWE Classification

CWE-248

References

github.com /bytecodealliance/wasmtime/security/advisories/GHSA-m758-wjhj-p3jq

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    "published": "2026-04-09T18:36:51.370Z",
    "modified": "2026-04-09T18:36:51.370Z",
    "type": "cve",
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