Vulnerability-Lookup

rustsec-2026-0006

Vulnerability from osv_rustsec

Published

2026-01-26 12:00

Modified

2026-01-30 05:41

Summary

Wasmtime segfault or unused out-of-sandbox load with `f64.copysign` operator on x86-64

Details

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-vc8c-j3xm-xj73 For more information see the GitHub-hosted security advisory.

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "categories": [],
        "cvss": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/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": "29.0.0"
            },
            {
              "fixed": "36.0.5"
            },
            {
              "introduced": "37.0.0"
            },
            {
              "fixed": "40.0.3"
            },
            {
              "introduced": "41.0.0"
            },
            {
              "fixed": "41.0.1"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "CVE-2026-24116",
    "GHSA-vc8c-j3xm-xj73"
  ],
  "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-vc8c-j3xm-xj73\nFor more information see the GitHub-hosted security advisory.",
  "id": "RUSTSEC-2026-0006",
  "modified": "2026-01-30T05:41:11Z",
  "published": "2026-01-26T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/wasmtime"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0006.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-vc8c-j3xm-xj73"
    }
  ],
  "related": [],
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Wasmtime segfault or unused out-of-sandbox load with `f64.copysign` operator on x86-64"
}

CVE-2026-24116 (GCVE-0-2026-24116)

Vulnerability from cvelistv5 – Published: 2026-01-27 18:58 – Updated: 2026-01-27 19:23

Title

Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64

Summary

Wasmtime is a runtime for WebAssembly. Starting in version 29.0.0 and prior to version 36.0.5, 40.0.3, and 41.0.1, on x86-64 platforms with AVX, Wasmtime's compilation of the `f64.copysign` WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it's possible for out-of-sandbox data to be loaded, but unless there is another bug in Cranelift this data is not visible to WebAssembly guests. Wasmtime 36.0.5, 40.0.3, and 41.0.1 have been released to fix this issue. Users are recommended to upgrade to the patched versions of Wasmtime. Other affected versions are not patched and users should updated to supported major version instead. This bug can be worked around by enabling signals-based-traps. While disabling guard pages can be a quick fix in some situations, it's not recommended to disabled guard pages as it is a key defense-in-depth measure of Wasmtime.

Severity ?

4.1 (Medium)


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

CWE

CWE-125 - Out-of-bounds Read

Assigner

GitHub_M

References

URL

Tags

	https://github.com/bytecodealliance/wasmtime/secu…	x_refsource_CONFIRM
	https://github.com/bytecodealliance/wasmtime/comm…	x_refsource_MISC
	https://github.com/bytecodealliance/wasmtime/comm…	x_refsource_MISC
	https://github.com/bytecodealliance/wasmtime/comm…	x_refsource_MISC
	https://docs.rs/wasmtime/latest/wasmtime/struct.C…	x_refsource_MISC
	https://docs.rs/wasmtime/latest/wasmtime/struct.C…	x_refsource_MISC
	https://docs.wasmtime.dev/stability-release.html	x_refsource_MISC
	https://rustsec.org/advisories/RUSTSEC-2026-0006.html	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	bytecodealliance	wasmtime	Affected: >= 29.0.0, < 36.0.5 Affected: >= 37.0.0, < 40.0.3 Affected: = 41.0.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-24116",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-01-27T19:22:29.285417Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-01-27T19:23:09.391Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "wasmtime",
          "vendor": "bytecodealliance",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 29.0.0, \u003c 36.0.5"
            },
            {
              "status": "affected",
              "version": "\u003e= 37.0.0, \u003c 40.0.3"
            },
            {
              "status": "affected",
              "version": "= 41.0.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Wasmtime is a runtime for WebAssembly. Starting in version 29.0.0 and prior to version 36.0.5, 40.0.3, and 41.0.1, on x86-64 platforms with AVX, Wasmtime\u0027s compilation of the `f64.copysign` WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it\u0027s possible for out-of-sandbox data to be loaded, but unless there is another bug in Cranelift this data is not visible to WebAssembly guests. Wasmtime 36.0.5, 40.0.3, and 41.0.1 have been released to fix this issue. Users are recommended to upgrade to the patched versions of Wasmtime. Other affected versions are not patched and users should updated to supported major version instead. This bug can be worked around by enabling signals-based-traps. While disabling guard pages can be a quick fix in some situations, it\u0027s not recommended to disabled guard pages as it is a key defense-in-depth measure of Wasmtime."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "LOCAL",
            "baseScore": 4.1,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "LOW",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "ACTIVE",
            "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/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-125",
              "description": "CWE-125: Out-of-bounds Read",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-01-27T18:58:52.349Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-vc8c-j3xm-xj73",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-vc8c-j3xm-xj73"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/commit/728fa07184f8da2a046f48ef9b61f869dce133a6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/commit/728fa07184f8da2a046f48ef9b61f869dce133a6"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/commit/799585fc362fcb991de147dd1a9f2ba0861ed440",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/commit/799585fc362fcb991de147dd1a9f2ba0861ed440"
        },
        {
          "name": "https://github.com/bytecodealliance/wasmtime/commit/ac92d9bb729ad3a6d93f0724c4c33a0c4a9c0227",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/bytecodealliance/wasmtime/commit/ac92d9bb729ad3a6d93f0724c4c33a0c4a9c0227"
        },
        {
          "name": "https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.memory_guard_size",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.memory_guard_size"
        },
        {
          "name": "https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.signals_based_traps",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.signals_based_traps"
        },
        {
          "name": "https://docs.wasmtime.dev/stability-release.html",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://docs.wasmtime.dev/stability-release.html"
        },
        {
          "name": "https://rustsec.org/advisories/RUSTSEC-2026-0006.html",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://rustsec.org/advisories/RUSTSEC-2026-0006.html"
        }
      ],
      "source": {
        "advisory": "GHSA-vc8c-j3xm-xj73",
        "discovery": "UNKNOWN"
      },
      "title": "Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-24116",
    "datePublished": "2026-01-27T18:58:52.349Z",
    "dateReserved": "2026-01-21T18:38:22.472Z",
    "dateUpdated": "2026-01-27T19:23:09.391Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

GHSA-VC8C-J3XM-XJ73

Vulnerability from github – Published: 2026-01-27 00:48 – Updated: 2026-01-29 03:28

Summary

Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64

Details

On x86-64 platforms with AVX Wasmtime's compilation of the f64.copysign WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it's possible for out-of-sandbox data to be loaded, but unless there is another bug in Cranelift this data is not visible to WebAssembly guests.

Details

The f64.copysign operator, when operating on a value loaded from a memory (for example with f64.load), compiles with Cranelift to code on x86-64 with AVX that loads 128 bits (16 bytes) rather than the expected 64 bits (8 bytes) from memory. When the address is in-bounds for a (correct) 8-byte load but not an (incorrect) 16-byte load, this can load beyond memory by up to 8 bytes. This can result in three different behaviors depending on Wasmtime's configuration:

If guard pages are disabled then this extra data will be loaded. The extra data is present in the upper bits of a register, but the upper bits are not visible to WebAssembly guests. Actually witnessing this data would require a different bug in Cranelift, of which none are known. Thus in this situation while it's something we're patching in Cranelift it's not a security issue.
If guard pages are enabled, and signals-based-traps are enabled, then this operation will result in a safe WebAssembly trap. The trap is incorrect because the load is not out-of-bounds as defined by WebAssembly, but this mistakenly widened load will load bytes from an unmapped guard page, causing a segfault which is caught and handled as a Wasm trap. In this situation this is not a security issue, but we're patching Cranelift to fix the WebAssembly behavior.
If guard pages are enabled, and signals-based-traps are disabled, then this operation results in an uncaught segfault. Like the previous case with guard pages enabled this will load from an unmapped guard page. Unlike before, however, signals-based-traps are disabled meaning that signal handlers aren't configured. The resulting segfault will, by default, terminate the process. This is a security issue from a DoS perspective, but does not represent an arbitrary read or write from WebAssembly, for example.

Wasmtime's default configuration is case (2) in this case. That means that Wasmtime, by default, incorrectly executes this WebAssembly instruction but does not have insecure behavior.

Impact

If signals-based-traps are disabled and guard pages are enabled then guests can trigger an uncaught segfault in the host, likely aborting the host process. This represents, for example, a DoS vector for WebAssembly guests.

This bug does not affect Wasmtime's default configuration and requires signals-based-traps to be disabled. This bug only affects the x86-64 target with the AVX feature enabled and the Cranelift backend (Wasmtime's default backend).

Patches

Wasmtime 36.0.5, 40.0.3, and 41.0.1 have been released to fix this issue. Users are recommended to upgrade to the patched versions of Wasmtime. Other affected versions are not patched and users should updated to supported major version instead.

Workarounds

This bug can be worked around by enabling signals-based-traps. While disabling guard pages can be a quick fix in some situations, it's not recommended to disabled guard pages as it is a key defense-in-depth measure of Wasmtime.

Resources

Severity ?

4.1 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "29.0.0"
            },
            {
              "fixed": "36.0.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "37.0.0"
            },
            {
              "fixed": "40.0.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "41.0.0"
            },
            {
              "fixed": "41.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "41.0.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-24116"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-125"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-27T00:48:20Z",
    "nvd_published_at": "2026-01-27T19:16:16Z",
    "severity": "MODERATE"
  },
  "details": "On x86-64 platforms with AVX Wasmtime\u0027s compilation of the `f64.copysign` WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When [signals-based-traps] are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it\u0027s possible for out-of-sandbox data to be loaded, but unless there is another bug in Cranelift this data is not visible to WebAssembly guests.\n\n### Details\n\nThe `f64.copysign` operator, when operating on a value loaded from a memory (for example with `f64.load`), compiles with Cranelift to code on x86-64 with AVX that loads 128 bits (16 bytes) rather than the expected 64 bits (8 bytes) from memory. When the address is in-bounds for a (correct) 8-byte load but not an (incorrect) 16-byte load, this can load beyond memory by up to 8 bytes. This can result in three different behaviors depending on Wasmtime\u0027s configuration:\n\n1. If guard pages are disabled then this extra data will be loaded. The extra data is present in the upper bits of a register, but the upper bits are not visible to WebAssembly guests. Actually witnessing this data would require a different bug in Cranelift, of which none are known. Thus in this situation while it\u0027s something we\u0027re patching in Cranelift it\u0027s not a security issue.\n2. If guard pages are enabled, and [signals-based-traps] are enabled, then this operation will result in a safe WebAssembly trap. The trap is incorrect because the load is not out-of-bounds as defined by WebAssembly, but this mistakenly widened load will load bytes from an unmapped guard page, causing a segfault which is caught and handled as a Wasm trap. In this situation this is not a security issue, but we\u0027re patching Cranelift to fix the WebAssembly behavior.\n3. If guard pages are enabled, and [signals-based-traps] are disabled, then this operation results in an uncaught segfault. Like the previous case with guard pages enabled this will load from an unmapped guard page. Unlike before, however, signals-based-traps are disabled meaning that signal handlers aren\u0027t configured. The resulting segfault will, by default, terminate the process. This is a security issue from a DoS perspective, but does not represent an arbitrary read or write from WebAssembly, for example.\n\nWasmtime\u0027s default configuration is case (2) in this case. That means that Wasmtime, by default, incorrectly executes this WebAssembly instruction but does not have insecure behavior.\n\n### Impact\n\nIf [signals-based-traps] are disabled and guard pages are enabled then guests can trigger an uncaught segfault in the host, likely aborting the host process. This represents, for example, a DoS vector for WebAssembly guests.\n\nThis bug does not affect Wasmtime\u0027s default configuration and requires [signals-based-traps] to be disabled. This bug only affects the x86-64 target with the AVX feature enabled and the Cranelift backend (Wasmtime\u0027s default backend).\n\n### Patches\n\nWasmtime 36.0.5, 40.0.3, and 41.0.1 have been released to fix this issue. Users are recommended to upgrade to the patched versions of Wasmtime. Other affected versions [are not patched](https://docs.wasmtime.dev/stability-release.html) and users should updated to supported major version instead.\n\n### Workarounds\n\nThis bug can be worked around by enabling [signals-based-traps]. While disabling guard pages can be a quick fix in some situations, it\u0027s not recommended to disabled guard pages as it is a key defense-in-depth measure of Wasmtime.\n\n### Resources\n\n* [signals-based-traps configuration][signals-based-traps]\n* [guard pages configuration](https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.memory_guard_size)\n\n[signals-based-traps]: https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.signals_based_traps",
  "id": "GHSA-vc8c-j3xm-xj73",
  "modified": "2026-01-29T03:28:33Z",
  "published": "2026-01-27T00:48:20Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-vc8c-j3xm-xj73"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24116"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/commit/728fa07184f8da2a046f48ef9b61f869dce133a6"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/commit/799585fc362fcb991de147dd1a9f2ba0861ed440"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/commit/ac92d9bb729ad3a6d93f0724c4c33a0c4a9c0227"
    },
    {
      "type": "WEB",
      "url": "https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.memory_guard_size"
    },
    {
      "type": "WEB",
      "url": "https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.signals_based_traps"
    },
    {
      "type": "WEB",
      "url": "https://docs.wasmtime.dev/stability-release.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/bytecodealliance/wasmtime"
    },
    {
      "type": "WEB",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0006.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64"
}

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

rustsec-2026-0006

Vulnerability from osv_rustsec

CVE-2026-24116 (GCVE-0-2026-24116)

GHSA-VC8C-J3XM-XJ73

Details

Impact

Patches

Workarounds

Resources

Tags

Sightings

Nomenclature