bytecodealliance wasmtime up to 24.0.6/36.0.6/42.0.1/44.0.0 WIT Interface uncaught exception

Summaryinfo

A vulnerability, which was classified as problematic, was found in bytecodealliance wasmtime up to 24.0.6/36.0.6/42.0.1/44.0.0. This affects an unknown part of the component WIT Interface. Such manipulation leads to uncaught exception. This vulnerability is documented as CVE-2026-34943. The attack can be executed remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in bytecodealliance wasmtime up to 24.0.6/36.0.6/42.0.1/44.0.0 and classified as problematic. Affected by this issue is some unknown functionality of the component WIT Interface. The manipulation with an unknown input leads to a uncaught exception vulnerability. Using CWE to declare the problem leads to CWE-248. An exception is thrown from a function, but it is not caught. Impacted is availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-34943 since 03/31/2026. The exploitation is known to be difficult. The attack may be launched remotely. The exploitation needs additional levels of successful authentication. The technical details are unknown and an exploit is not available.

The vulnerability scanner Nessus provides a plugin with the ID 305823 (Linux Distros Unpatched Vulnerability : CVE-2026-34943), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 24.0.7, 36.0.7, 42.0.2 or 44.0.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (305823). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• bytecodealliance

Name

• wasmtime

Version

• 24.0.0
• 24.0.1
• 24.0.2
• 24.0.3
• 24.0.4
• 24.0.5
• 24.0.6
• 36.0.0
• 36.0.1
• 36.0.2
• 36.0.3
• 36.0.4
• 36.0.5
• 36.0.6
• 42.0.0
• 42.0.1
• 44.0

Website

• Product: https://github.com/bytecodealliance/wasmtime/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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