rust-wasmtime — security advisory

{
  "id": "d80448220ad9c84f6c85ccc51c812c0bf5fdac770ecd98129294529d61707810",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-34971",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-34971",
    "summary": "Wasmtime is a runtime for WebAssembly. From 32.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Cranelift compilation backend contains a bug on aarch64 when performing a certain shape of heap accesses which means that the wrong address is accessed. When combined with explicit bounds checks a guest WebAssembly module this can create a situation where there are two diverging computations for the same address: one for the address to bounds-check and one for the address to load. This difference in address being operated on means that a guest module can pass a bounds check but then load a different address. Combined together this enables an arbitrary read/write primitive for guest WebAssembly when accesssing host memory. This is a sandbox escape as guests are able to read/write arbitrary host memory. This vulnerability has a few ingredients, all of which must be met, for this situation to occur and bypass the sandbox restrictions. This miscompiled shape of load only occurs on 64-bit WebAssembly linear memories, or when Config::wasm_memory64 is enabled. 32-bit WebAssembly is not affected. Spectre mitigations or signals-based-traps must be disabled. When spectre mitigations are enabled then the offending shape of load is not generated. When signals-based-traps are disabled then spectre mitigations are also automatically disabled. The specific bug in Cranelift is a miscompile of a load of the shape load(iadd(base, ishl(index, amt))) where amt is a constant. The amt value is maske",
    "evidence": "osv:UBUNTU-CVE-2026-34971",
    "products": [
      {
        "name": {
          "value": "rust-wasmtime",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "10.0.1+dfsg-7",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "15.0.1+dfsg-4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "16.0.0+dfsg-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "16.0.0+dfsg-3",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "rust-wasmtime",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "26.0.1+dfsg-3",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "rust-wasmtime",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "36.0.5+dfsg-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "36.0.13+dfsg-1",
            "evidence": "/affected/2/versions"
          }
        ]
      },
      {
        "name": {
          "value": "rust-wasmtime",
          "evidence": "/affected/3/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "26.0.1+dfsg-3",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "26.0.1+dfsg-4",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "28.0.1+dfsg-3",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "29.0.1+dfsg-5",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "36.0.5+dfsg-1",
            "evidence": "/affected/3/versions"
          }
        ]
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "UBUNTU-CVE-2026-34971",
      "aliases": [
        "UBUNTU-CVE-2026-34971"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H"
        },
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H"
        },
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "rust-wasmtime",
            "purl": "pkg:deb/ubuntu/rust-wasmtime?arch=source&distro=noble",
            "ecosystem": "Ubuntu:24.04:LTS"
          },
          "versions": [
            "10.0.1+dfsg-7",
            "15.0.1+dfsg-4",
            "16.0.0+dfsg-2",
            "16.0.0+dfsg-3"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34971.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "librust-cranelift-dev",
                "binary_version": "0.103.0+16.0.0+dfsg-3"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "rust-wasmtime",
            "purl": "pkg:deb/ubuntu/rust-wasmtime?arch=source&distro=questing",
            "ecosystem": "Ubuntu:25.10"
          },
          "versions": [
            "26.0.1+dfsg-3"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34971.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "librust-cranelift-dev",
                "binary_version": "0.113.1+26.0.1+dfsg-3"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "rust-wasmtime",
            "purl": "pkg:deb/ubuntu/rust-wasmtime?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "36.0.5+dfsg-1",
            "36.0.13+dfsg-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34971.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "librust-cranelift-dev",
                "binary_version": "0.123.13+36.0.13+dfsg-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "rust-wasmtime",
            "purl": "pkg:deb/ubuntu/rust-wasmtime?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "26.0.1+dfsg-3",
            "26.0.1+dfsg-4",
            "28.0.1+dfsg-3",
            "29.0.1+dfsg-5",
            "36.0.5+dfsg-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34971.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "librust-cranelift-dev",
                "binary_version": "0.123.5+36.0.5+dfsg-1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T13:00:02.604031094Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-34971"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-34971",
        "https://www.cve.org/CVERecord?id=CVE-2026-34971",
        "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jhxm-h53p-jm7w"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-34971",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 360177,
  "published_at": "2026-04-09T19:16:00+00:00"
}