CVE-2026-104855 (GCVE-0-2026-104855)

Vulnerability from cvelistv5 – Published: 2026-10-02 17:37 – Updated: 2026-10-02 17:37
VLAI
Title
Wasmtime: Preemption and traps during bulk operations enable breaking internal VM state
Summary
Wasmtime is a runtime for WebAssembly. From 46.0.0 until 46.0.2 and 47.0.3, fuel and epoch preemption checks inside bulk operations including memory.copy, table.grow, and array.copy can expose invalid intermediate state when an embedder mutates a Store in Store::epoch_deadline_callback or continues using a Store after cancellation or a trap. A cancelled non-nullable table growth can leave null elements, linear-memory growth during memory.copy can invalidate retained raw pointers, and callback-triggered garbage collection during array.copy can invalidate GC pointers, resulting in a crash, invalid memory access, or GC heap corruption. Embeddings whose callbacks only access the host data in Store<T>, and embeddings that discard a Store after timeout or epoch deadline, are not affected. This issue is fixed in versions 46.0.2 and 47.0.3.
Severity
2 (Low)
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
CWE
  • CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Assigner
References
Impacted products
Vendor Product Version CPE status
bytecodealliance wasmtime Affected: >= 46.0.0, < 46.0.2
Affected: >= 47.0.0, < 47.0.3
guessed Create a notification for this product.
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "wasmtime",
          "vendor": "bytecodealliance",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 46.0.0, \u003c 46.0.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 47.0.0, \u003c 47.0.3"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Wasmtime is a runtime for WebAssembly. From 46.0.0 until 46.0.2 and 47.0.3, fuel and epoch preemption checks inside bulk operations including memory.copy, table.grow, and array.copy can expose invalid intermediate state when an embedder mutates a Store in Store::epoch_deadline_callback or continues using a Store after cancellation or a trap. A cancelled non-nullable table growth can leave null elements, linear-memory growth during memory.copy can invalidate retained raw pointers, and callback-triggered garbage collection during array.copy can invalidate GC pointers, resulting in a crash, invalid memory access, or GC heap corruption. Embeddings whose callbacks only access the host data in Store\u003cT\u003e, and embeddings that discard a Store after timeout or epoch deadline, are not affected. This issue is fixed in versions 46.0.2 and 47.0.3."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 2,
            "baseSeverity": "LOW",
            "privilegesRequired": "HIGH",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "PASSIVE",
            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-362",
              "description": "CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-02T17:37:50.941Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-2hw9-mc66-jc2q",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-2hw9-mc66-jc2q"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/pull/14041",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/pull/14041"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/pull/14043",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/pull/14043"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/pull/14045",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/pull/14045"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/commit/3ebfbe5af4927c157d6fcaca42b8dbb6d17b73fb",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/commit/3ebfbe5af4927c157d6fcaca42b8dbb6d17b73fb"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/commit/99b0bc39d447317a4102c056081c83a9a84a46e0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/commit/99b0bc39d447317a4102c056081c83a9a84a46e0"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/commit/a3eb27af01ba5a30320a90ea1405059cdfedd353",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/commit/a3eb27af01ba5a30320a90ea1405059cdfedd353"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/releases/tag/v46.0.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/releases/tag/v46.0.2"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/releases/tag/v47.0.3",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/releases/tag/v47.0.3"
        }
      ],
      "source": {
        "advisory": "GHSA-2hw9-mc66-jc2q",
        "discovery": "UNKNOWN"
      },
      "title": "Wasmtime: Preemption and traps during bulk operations enable breaking internal VM state"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-104855",
    "datePublished": "2026-10-02T17:37:50.941Z",
    "dateReserved": "2026-10-02T14:38:43.244Z",
    "dateUpdated": "2026-10-02T17:37:50.941Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "wasmtime",
                "vendor": "bytecodealliance",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003e= 46.0.0, \u003c 46.0.2"
                  },
                  {
                    "status": "affected",
                    "version": "\u003e= 47.0.0, \u003c 47.0.3"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Wasmtime is a runtime for WebAssembly. From 46.0.0 until 46.0.2 and 47.0.3, fuel and epoch preemption checks inside bulk operations including memory.copy, table.grow, and array.copy can expose invalid intermediate state when an embedder mutates a Store in Store::epoch_deadline_callback or continues using a Store after cancellation or a trap. A cancelled non-nullable table growth can leave null elements, linear-memory growth during memory.copy can invalidate retained raw pointers, and callback-triggered garbage collection during array.copy can invalidate GC pointers, resulting in a crash, invalid memory access, or GC heap corruption. Embeddings whose callbacks only access the host data in Store\u003cT\u003e, and embeddings that discard a Store after timeout or epoch deadline, are not affected. This issue is fixed in versions 46.0.2 and 47.0.3."
          }
        ],
        "id": "CVE-2026-104855",
        "lastModified": "2026-10-02T18:17:02.220",
        "metrics": {
          "cvssMetricV40": [
            {
              "cvssData": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "HIGH",
                "attackRequirements": "PRESENT",
                "attackVector": "NETWORK",
                "availabilityRequirement": "NOT_DEFINED",
                "baseScore": 2.0,
                "baseSeverity": "LOW",
                "confidentialityRequirement": "NOT_DEFINED",
                "exploitMaturity": "NOT_DEFINED",
                "integrityRequirement": "NOT_DEFINED",
                "modifiedAttackComplexity": "NOT_DEFINED",
                "modifiedAttackRequirements": "NOT_DEFINED",
                "modifiedAttackVector": "NOT_DEFINED",
                "modifiedPrivilegesRequired": "NOT_DEFINED",
                "modifiedSubAvailabilityImpact": "NOT_DEFINED",
                "modifiedSubConfidentialityImpact": "NOT_DEFINED",
                "modifiedSubIntegrityImpact": "NOT_DEFINED",
                "modifiedUserInteraction": "NOT_DEFINED",
                "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
                "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
                "modifiedVulnIntegrityImpact": "NOT_DEFINED",
                "privilegesRequired": "HIGH",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "NONE",
                "subIntegrityImpact": "NONE",
                "userInteraction": "PASSIVE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:L/VA:L/SC:N/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",
                "version": "4.0",
                "vulnAvailabilityImpact": "LOW",
                "vulnConfidentialityImpact": "NONE",
                "vulnIntegrityImpact": "LOW",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-10-02T18:17:02.083",
        "references": [
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/bytecodealliance/wasmtime/commit/3ebfbe5af4927c157d6fcaca42b8dbb6d17b73fb"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/bytecodealliance/wasmtime/commit/99b0bc39d447317a4102c056081c83a9a84a46e0"
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            "url": "https://github.com/bytecodealliance/wasmtime/pull/14041"
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            "url": "https://github.com/bytecodealliance/wasmtime/pull/14043"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/bytecodealliance/wasmtime/pull/14045"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/bytecodealliance/wasmtime/releases/tag/v46.0.2"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/bytecodealliance/wasmtime/releases/tag/v47.0.3"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-2hw9-mc66-jc2q"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Deferred",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-362"
              }
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            "source": "security-advisories@github.com",
            "type": "Primary"
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    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-02T19:50:14+00:00",
      "cve": "CVE-2026-104855",
      "id": "CVE-2026-104855",
      "initial_release_date": "2026-10-02T17:37:50.941000+00:00",
      "product_status:known_affected": "4",
      "product_status:known_not_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "wasmtime: wasmtime: Memory corruption via preemption checks during bulk operations",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-104855.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.