CVE-2026-34942
Full vulnerability record from the local CVENow database.
Description
Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of transcoding strings into the Component Model's utf16 or latin1+utf16 encodings improperly verified the alignment of reallocated strings. This meant that unaligned pointers could be passed to the host for transcoding which would trigger a host panic. This panic is possible to trigger from malicious guests which transfer very specific strings across components with specific addresses. Host panics are considered a DoS vector in Wasmtime as the panic conditions are controlled by the guest in this situation. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.
Severity
MEDIUM
CVSS score
5.9
(v4.0)
Vulnerability status
Analyzed
Source identifier
Published
2026-04-09 19:16:23.857000
Last modified
2026-10-26 21:10:00.170000
View original CVE JSON
{
"id": "CVE-2026-34942",
"sourceIdentifier": "[email protected]",
"published": "2026-04-09T19:16:23.857",
"lastModified": "2026-10-26T21:10:00.170",
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"value": "Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of transcoding strings into the Component Model's utf16 or latin1+utf16 encodings improperly verified the alignment of reallocated strings. This meant that unaligned pointers could be passed to the host for transcoding which would trigger a host panic. This panic is possible to trigger from malicious guests which transfer very specific strings across components with specific addresses. Host panics are considered a DoS vector in Wasmtime as the panic conditions are controlled by the guest in this situation. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1."
},
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"value": "Wasmtime es un entorno de ejecución para WebAssembly. Antes de 24.0.7, 36.0.7, 42.0.2 y 43.0.1, la implementación de Wasmtime para la transcodificación de cadenas a las codificaciones utf16 o latin1+utf16 del Modelo de Componentes verificaba incorrectamente la alineación de las cadenas reasignadas. Esto significaba que se podían pasar punteros no alineados al host para la transcodificación, lo que desencadenaría un pánico del host. Este pánico es posible de desencadenar desde invitados maliciosos que transfieren cadenas muy específicas entre componentes con direcciones específicas. Los pánicos del host se consideran un vector de DoS en Wasmtime, ya que las condiciones de pánico son controladas por el invitado en esta situación. Esta vulnerabilidad está corregida en 24.0.7, 36.0.7, 42.0.2 y 43.0.1."
}
],
"affected": [
{
"source": "[email protected]",
"affectedData": [
{
"vendor": "bytecodealliance",
"product": "wasmtime",
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"status": "affected"
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}