CVE-2026-34945

{
  "id": "CVE-2026-34945",
  "sourceIdentifier": "[email protected]",
  "published": "2026-04-09T19:16:24.330",
  "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 contains a bug where a 64-bit table, part of the memory64 proposal of WebAssembly, incorrectly translated the table.size instruction. This bug could lead to disclosing data on the host's stack to WebAssembly guests. The host's stack can possibly contain sensitive data related to other host-originating operations which is not intended to be disclosed to guests. This bug specifically arose from a mistake where the return value of table.size was statically typed as a 32-bit integer, as opposed to consulting the table's index type to see how large the returned register could be. When combined with details about Wnich's ABI, such as multi-value returns, this can be combined to read stack data from the host, within a guest. 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 compilador Winch de Wasmtime contiene un error donde una tabla de 64 bits, parte de la propuesta memory64 de WebAssembly, traducía incorrectamente la instrucción table.size. Este error podría llevar a la divulgación de datos de la pila del anfitrión a los invitados de WebAssembly. La pila del anfitrión posiblemente puede contener datos sensibles relacionados con otras operaciones originadas en el anfitrión que no están destinados a ser divulgados a los invitados. Este error surgió específicamente de un fallo donde el valor de retorno de table.size fue tipado estáticamente como un entero de 32 bits, en lugar de consultar el tipo de índice de la tabla para ver cuán grande podría ser el registro devuelto. Cuando se combina con detalles sobre la ABI de Winch, como los retornos de múltiples valores, esto puede combinarse para leer datos de la pila del anfitrión, dentro de un invitado. Esta vulnerabilidad está corregida 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"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV40": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "baseScore": 2.3,
          "baseSeverity": "LOW",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "vulnConfidentialityImpact": "LOW",
          "vulnIntegrityImpact": "NONE",
          "vulnAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "NONE",
          "subAvailabilityImpact": "NONE",
          "exploitMaturity": "NOT_DEFINED",
          "confidentialityRequirement": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "valueDensity": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Primary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-04-10T14:12:11.204857Z",
          "id": "CVE-2026-34945",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-681"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*",
              "versionStartIncluding": "25.0.0",
              "versionEndExcluding": "36.0.7",
              "matchCriteriaId": "B5AB2157-3977-49F9-9058-6B16A2556170"
            },
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*",
              "versionStartIncluding": "37.0.0",
              "versionEndExcluding": "42.0.2",
              "matchCriteriaId": "1D7B70EB-93E3-4732-AB70-E6A531178941"
            },
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*",
              "versionStartIncluding": "43.0.0",
              "versionEndExcluding": "43.0.1",
              "matchCriteriaId": "15FD6AA4-973B-4647-9222-40FBDC16A6FD"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-m9w2-8782-2946",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
    }
  ]
}