CVE-2026-35186

{
  "id": "CVE-2026-35186",
  "sourceIdentifier": "[email protected]",
  "published": "2026-04-09T19:16:25.343",
  "lastModified": "2026-10-26T22:10:00.163",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1."
    },
    {
      "lang": "es",
      "value": "Wasmtime es un entorno de ejecución para WebAssembly. Desde la versión 25.0.0 hasta antes de las versiones 36.0.7, 42.0.2 y 43.0.1, el backend del compilador Winch de Wasmtime contiene un error donde la traducción del operador table.grow hace que el resultado tenga un tipo incorrecto. Para tablas de 32 bits, esto significa que el resultado del operador, internamente en Winch, se etiqueta como un valor de 64 bits en lugar de un valor de 32 bits. Esta representación interna inválida del estado del compilador de Winch se agrava en problemas adicionales dependiendo de cómo se consume el valor. La consecuencia principal de este error es que se pueden almacenar/leer bytes del espacio de direcciones del host. Esto solo es aplicable a los 16 bytes antes de la memoria lineal, sin embargo, ya que el único valor de retorno significativo de table.grow que puede ser malinterpretado es -1. Los bytes antes de la memoria lineal son, por defecto, memoria no mapeada. Wasmtime detectará este fallo y abortará el proceso, sin embargo, porque wasm no debería poder acceder a estos bytes. En general, este error en Winch representa un vector de DoS al bloquear el proceso del host, un problema de corrección dentro de Winch y una posible fuga de hasta 16 bytes antes de la memoria lineal. El compilador predeterminado de Wasmtime es Cranelift, no Winch, y la configuración predeterminada de Wasmtime es colocar páginas de guardia antes de la memoria lineal. Esto significa que la configuración predeterminada de Wasmtime no se ve afectada por este problema, y al elegir explícitamente Winch, la configuración por defecto de Wasmtime, de lo contrario, conduce a un DoS. Deshabilitar las páginas de guardia antes de la memoria lineal es necesario para posiblemente filtrar hasta 16 bytes de datos del host. Esta vulnerabilidad se corrige en las versiones 36.0.7, 42.0.2 y 43.0.1."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "bytecodealliance",
          "product": "wasmtime",
          "versions": [
            {
              "version": ">= 25.0.0, < 36.0.7",
              "status": "affected"
            },
            {
              "version": ">= 37.0.0, < 42.0.2",
              "status": "affected"
            },
            {
              "version": ">= 43.0.0, < 44.0.1",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
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          "modifiedAttackRequirements": "NOT_DEFINED",
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          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
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          "valueDensity": "NOT_DEFINED",
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        "ssvcData": {
          "timestamp": "2026-04-13T20:17:58.130808Z",
          "id": "CVE-2026-35186",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
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            {
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            }
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          "role": "CISA Coordinator",
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  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-789"
        }
      ]
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  "references": [
    {
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-f984-pcp8-v2p7",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
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}