Vulnerability-Lookup

GHSA-Q49F-XG75-M9XW

Vulnerability from github – Published: 2026-04-09 20:23 – Updated: 2026-04-10 14:39

Summary

Wasmtime has host panic when Winch compiler executes `table.fill`

Details

Impact

Wasmtime's Winch compiler contains a vulnerability where the compilation of the table.fill instruction can result in a host panic. This means that a valid guest can be compiled with Winch, on any architecture, and cause the host to panic. This represents a denial-of-service vulnerability in Wasmtime due to guests being able to trigger a panic.

The specific issue is that a historical refactoring, #11254, changed how compiled code referenced tables within the table.* instructions. This refactoring forgot to update the Winch code paths associated as well, meaning that Winch was using the wrong indexing scheme. Due to the feature support of Winch the only problem that can result is tables being mixed up or nonexistent tables being used, meaning that the guest is limited to panicking the host (using a nonexistent table), or executing spec-incorrect behavior and modifying the wrong table.

Patches

Wasmtime 36.0.7, 42.0.2, and 43.0.1 have been issued to fix this bug. Users are recommended to update to these patched versions of Wasmtime.

Workarounds

Users of Cranelift are not affected by this issue, but for users of Winch there is no workaround for this bug. Hosts are recommended to updated to a patched version of Wasmtime.

Severity ?

5.9 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "25.0.0"
            },
            {
              "fixed": "36.0.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "37.0.0"
            },
            {
              "fixed": "42.0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "43.0.0"
            },
            {
              "fixed": "43.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "43.0.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34946"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248",
      "CWE-670"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-09T20:23:21Z",
    "nvd_published_at": "2026-04-09T19:16:24Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nWasmtime\u0027s Winch compiler contains a vulnerability where the compilation of the `table.fill` instruction can result in a host panic. This means that a valid guest can be compiled with Winch, on any architecture, and cause the host to panic. This represents a denial-of-service vulnerability in Wasmtime due to guests being able to trigger a panic.\n\nThe specific issue is that a historical refactoring, #11254, changed how compiled code referenced tables within the `table.*` instructions. This refactoring forgot to update the Winch code paths associated as well, meaning that Winch was using the wrong indexing scheme. Due to the feature support of Winch the only problem that can result is tables being mixed up or nonexistent tables being used, meaning that the guest is limited to panicking the host (using a nonexistent table), or executing spec-incorrect behavior and modifying the wrong table.\n\n### Patches\n\nWasmtime 36.0.7, 42.0.2, and 43.0.1 have been issued to fix this bug. Users are recommended to update to these patched versions of Wasmtime.\n\n### Workarounds\n\nUsers of Cranelift are not affected by this issue, but for users of Winch there is no workaround for this bug. Hosts are recommended to updated to a patched version of Wasmtime.",
  "id": "GHSA-q49f-xg75-m9xw",
  "modified": "2026-04-10T14:39:39Z",
  "published": "2026-04-09T20:23:21Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q49f-xg75-m9xw"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34946"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/bytecodealliance/wasmtime"
    },
    {
      "type": "WEB",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0089.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Wasmtime has host panic when Winch compiler executes `table.fill`"
}

rustsec-2026-0089

Vulnerability from osv_rustsec

Published

2026-04-09 12:00

Modified

2026-04-09 19:59

Summary

Host panic when Winch compiler executes `table.fill`

Details

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q49f-xg75-m9xw For more information see the GitHub-hosted security advisory.

Severity

5.9 (Medium)


                    
                      CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

URL

Type

	https://crates.io/crates/wasmtime	PACKAGE
	https://rustsec.org/advisories/RUSTSEC-2026-0089.html	ADVISORY
	https://github.com/bytecodealliance/wasmtime/secu…	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "categories": [],
        "cvss": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime",
        "purl": "pkg:cargo/wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "36.0.7"
            },
            {
              "introduced": "37.0.0"
            },
            {
              "fixed": "42.0.2"
            },
            {
              "introduced": "43.0.0"
            },
            {
              "fixed": "43.0.1"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "CVE-2026-34946",
    "GHSA-q49f-xg75-m9xw"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "This is an entry in the RustSec database for the Wasmtime security advisory\nlocated at\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q49f-xg75-m9xw\nFor more information see the GitHub-hosted security advisory.",
  "id": "RUSTSEC-2026-0089",
  "modified": "2026-04-09T19:59:38Z",
  "published": "2026-04-09T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/wasmtime"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0089.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q49f-xg75-m9xw"
    }
  ],
  "related": [],
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Host panic when Winch compiler executes `table.fill`"
}

CVE-2026-34946 (GCVE-0-2026-34946)

Vulnerability from cvelistv5 – Published: 2026-04-09 18:43 – Updated: 2026-04-09 19:33

Title

Wasmtime's host panics when Winch compiler executes `table.fill`

Summary

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 vulnerability where the compilation of the table.fill instruction can result in a host panic. This means that a valid guest can be compiled with Winch, on any architecture, and cause the host to panic. This represents a denial-of-service vulnerability in Wasmtime due to guests being able to trigger a panic. The specific issue is that a historical refactoring changed how compiled code referenced tables within the table.* instructions. This refactoring forgot to update the Winch code paths associated as well, meaning that Winch was using the wrong indexing scheme. Due to the feature support of Winch the only problem that can result is tables being mixed up or nonexistent tables being used, meaning that the guest is limited to panicking the host (using a nonexistent table), or executing spec-incorrect behavior and modifying the wrong table. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.

Severity ?

5.9 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CWE

CWE-670 - Always-Incorrect Control Flow Implementation

Assigner

GitHub_M

References

URL

Tags

https://github.com/bytecodealliance/wasmtime/secu…

x_refsource_CONFIRM

Impacted products

	Vendor	Product	Version
	bytecodealliance	wasmtime	Affected: >= 25.0.0, < 36.0.7 Affected: >= 37.0.0, < 42.0.2 Affected: >= 43.0.0, < 44.0.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-34946",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-09T19:33:22.517926Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-09T19:33:33.709Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "wasmtime",
          "vendor": "bytecodealliance",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 25.0.0, \u003c 36.0.7"
            },
            {
              "status": "affected",
              "version": "\u003e= 37.0.0, \u003c 42.0.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 43.0.0, \u003c 44.0.1"
            }
          ]
        }
      ],
      "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\u0027s Winch compiler contains a vulnerability where the compilation of the table.fill instruction can result in a host panic. This means that a valid guest can be compiled with Winch, on any architecture, and cause the host to panic. This represents a denial-of-service vulnerability in Wasmtime due to guests being able to trigger a panic. The specific issue is that a historical refactoring changed how compiled code referenced tables within the table.* instructions. This refactoring forgot to update the Winch code paths associated as well, meaning that Winch was using the wrong indexing scheme. Due to the feature support of Winch the only problem that can result is tables being mixed up or nonexistent tables being used, meaning that the guest is limited to panicking the host (using a nonexistent table), or executing spec-incorrect behavior and modifying the wrong table. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "LOW",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "PASSIVE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-670",
              "description": "CWE-670: Always-Incorrect Control Flow Implementation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-09T18:43:39.137Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q49f-xg75-m9xw",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q49f-xg75-m9xw"
        }
      ],
      "source": {
        "advisory": "GHSA-q49f-xg75-m9xw",
        "discovery": "UNKNOWN"
      },
      "title": "Wasmtime\u0027s host panics when Winch compiler executes `table.fill`"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-34946",
    "datePublished": "2026-04-09T18:43:39.137Z",
    "dateReserved": "2026-03-31T17:27:08.661Z",
    "dateUpdated": "2026-04-09T19:33:33.709Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
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.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-Q49F-XG75-M9XW

Impact

Patches

Workarounds

rustsec-2026-0089

Vulnerability from osv_rustsec

CVE-2026-34946 (GCVE-0-2026-34946)

Tags

Sightings

Nomenclature