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.

Attack Vector Network

Attack Complexity High

Privileges Required High

Attack Requirements Present

User Interaction Active

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
bytecodealliance wasmtime affected
Version Status Constraints
< 24.0.7 affected —
>= 25.0.0, < 36.0.7 affected —
>= 37.0.0, < 42.0.2 affected —
>= 43.0.0, < 44.0.1 affected —

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Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-m758-wjhj-p3jq Wasmtime has a possible panic when lifting `flags` component value
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-m758-wjhj-p3jq cve-icon cve-icon
History

Thu, 09 Apr 2026 19:00:00 +0000

Type Values Removed Values Added
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.
Title Wasmtime panics when lifting `flags` component value
Weaknesses CWE-248
References
Metrics cvssV4_0

{'score': 5.6, 'vector': '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-04-09T18:36:51.370Z

Reserved: 2026-03-31T17:27:08.660Z

Link: CVE-2026-34943

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-04-09T19:16:24.020

Modified: 2026-04-09T19:16:24.020

Link: CVE-2026-34943

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses