cvelistv5 - cve-2025-64345

CVE-2025-64345 (GCVE-0-2025-64345)

Vulnerability from cvelistv5 – Published: 2025-11-12 21:25 – Updated: 2025-11-12 21:40

Summary

Wasmtime is a runtime for WebAssembly. Prior to version 38.0.4, 37.0.3, 36.0.3, and 24.0.5, Wasmtime's Rust embedder API contains an unsound interaction where a WebAssembly shared linear memory could be viewed as a type which provides safe access to the host (Rust) to the contents of the linear memory. This is not sound for shared linear memories, which could be modified in parallel, and this could lead to a data race in the host. Patch releases have been issued for all supported versions of Wasmtime, notably: 24.0.5, 36.0.3, 37.0.3, and 38.0.4. These releases reject creation of shared memories via `Memory::new` and shared memories are now excluded from core dumps. As a workaround, eembeddings affected by this issue should use `SharedMemory::new` instead of `Memory::new` to create shared memories. Affected embeddings should also disable core dumps if they are unable to upgrade. Note that core dumps are disabled by default but the wasm threads proposal (and shared memory) is enabled by default.

Severity ?

1.8 (Low)


                        
                          CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N

CWE

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

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://docs.rs/wasmtime/latest/wasmtime/struct.M…	x_refsource_MISC
	https://docs.rs/wasmtime/latest/wasmtime/struct.S…	x_refsource_MISC
	https://docs.wasmtime.dev/stability-release.html	x_refsource_MISC
	https://github.com/bytecodealliance/wasmtime/rele…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	bytecodealliance	wasmtime	Affected: >= 38.0.1, < 38.0.4 Affected: >= 37.0.0, < 37.0.3 Affected: >= 26.0.0, < 36.0.3 Affected: < 24.0.5

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2025-64345

Vulnerability from fkie_nvd - Published: 2025-11-12 22:15 - Updated: 2025-11-14 16:42

Severity ?

1.8 (Low) - CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://docs.rs/wasmtime/latest/wasmtime/struct.Memory.html#method.new
	security-advisories@github.com	https://docs.rs/wasmtime/latest/wasmtime/struct.SharedMemory.html#method.new
	security-advisories@github.com	https://docs.wasmtime.dev/stability-release.html
	security-advisories@github.com	https://github.com/bytecodealliance/wasmtime/commit/9ebb6934f00d58b92fb68ed0e0b16c0ae828ca10
	security-advisories@github.com	https://github.com/bytecodealliance/wasmtime/releases/tag/v38.0.4
	security-advisories@github.com	https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hc7m-r6v8-hg9q

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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GHSA-HC7M-R6V8-HG9Q

Vulnerability from github – Published: 2025-11-12 21:36 – Updated: 2025-11-13 22:02

Summary

Wasmtime provides unsound API access to a WebAssembly shared linear memory

Details

Impact

Wasmtime's Rust embedder API contains an unsound interaction where a WebAssembly shared linear memory could be viewed as a type which provides safe access to the host (Rust) to the contents of the linear memory. This is not sound for shared linear memories, which could be modified in parallel, and this could lead to a data race in the host.

Wasmtime has a wasmtime::Memory type which represents linear memories in a WebAssembly module. Wasmtime also has wasmtime::SharedMemory, however, which represents shared linear memories introduced in the WebAssembly threads proposal. The API of SharedMemory does not provide accessors which return &[u8] in Rust, for example, as that's not a sound type signature when other threads could be modifying memory. The wasmtime::Memory type, however, does provide this API as it's intended to be used with non-shared memories where static knowledge is available that no concurrent or parallel reads or writes are happening. This means that it's not sound to represent a shared linear memory with wasmtime::Memory and it must instead be represented with wasmtime::SharedMemory.

There were two different, erroneous, methods of creating a wasmtime::Memory which represents a shared memory however:

The wasmtime::Memory::new constructor takes a MemoryType which could be shared. This function did not properly reject shared memory types and require usage of SharedMemory::new instead.
Capturing a core dump with WebAssembly would expose all linear memories a wasmtime::Memory. This means that a core dump would perform an unsynchronized read of shared linear memory, possibly leading to data races.

This is a bug in Wasmtime's safe Rust API. It should not be possible to cause unsoundness with Wasmtime's embedding API if unsafe is not used. Embeddings which do not use the wasm threads proposal nor created shared memories nor actually share shared memories across threads are unaffected. Only if shared memories are created across threads might an embedding be affected.

Patches

Patch releases have been issued for all supported versions of Wasmtime, notably: 24.0.5, 36.0.3, 37.0.3, and 38.0.4. These releases reject creation of shared memories via Memory::new and shared memories are now excluded from core dumps.

Workarounds

Embeddings affected by this issue should use SharedMemory::new instead of Memory::new to create shared memories. Affected embeddings should also disable core dumps if they are unable to upgrade. Note that core dumps are disabled by default but the wasm threads proposal (and shared memory) is enabled by default. It's recommended to upgrade to a patched version of Wasmtime, however.

Severity ?

1.8 (Low)


                  
                    CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N

Show details on source website

JSON

To clipboard

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            },
            {
              "fixed": "24.0.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-64345"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-362"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-11-12T21:36:29Z",
    "nvd_published_at": "2025-11-12T22:15:49Z",
    "severity": "LOW"
  },
  "details": "### Impact\n\nWasmtime\u0027s Rust embedder API contains an unsound interaction where a WebAssembly shared linear memory could be viewed as a type which provides safe access to the host (Rust) to the contents of the linear memory. This is not sound for shared linear memories, which could be modified in parallel, and this could lead to a data race in the host.\n\nWasmtime has a `wasmtime::Memory` type which represents linear memories in a WebAssembly module. Wasmtime also has `wasmtime::SharedMemory`, however, which represents shared linear memories introduced in the WebAssembly `threads` proposal. The API of `SharedMemory` does not provide accessors which return `\u0026[u8]` in Rust, for example, as that\u0027s not a sound type signature when other threads could be modifying memory. The `wasmtime::Memory` type, however, does provide this API as it\u0027s intended to be used with non-shared memories where static knowledge is available that no concurrent or parallel reads or writes are happening. This means that it\u0027s not sound to represent a shared linear memory with `wasmtime::Memory` and it must instead be represented with `wasmtime::SharedMemory`.\n\nThere were two different, erroneous, methods of creating a `wasmtime::Memory` which represents a shared memory however:\n\n1. The [`wasmtime::Memory::new` constructor](https://docs.rs/wasmtime/latest/wasmtime/struct.Memory.html#method.new) takes a `MemoryType` which could be `shared`. This function did not properly reject shared memory types and require usage of [`SharedMemory::new`](https://docs.rs/wasmtime/latest/wasmtime/struct.SharedMemory.html#method.new) instead.\n2. Capturing a core dump with WebAssembly would expose all linear memories a `wasmtime::Memory`. This means that a core dump would perform an unsynchronized read of shared linear memory, possibly leading to data races.\n\nThis is a bug in Wasmtime\u0027s safe Rust API. It should not be possible to cause unsoundness with Wasmtime\u0027s embedding API if `unsafe` is not used. Embeddings which do not use the wasm threads proposal nor created shared memories nor actually share shared memories across threads are unaffected. Only if shared memories are created across threads might an embedding be affected.\n\n### Patches\n\nPatch releases have been issued for [all supported versions of Wasmtime](https://docs.wasmtime.dev/stability-release.html), notably: 24.0.5, 36.0.3, 37.0.3, and 38.0.4. These releases reject creation of shared memories via `Memory::new` and shared memories are now excluded from core dumps. \n\n### Workarounds\n\nEmbeddings affected by this issue should use `SharedMemory::new` instead of `Memory::new` to create shared memories. Affected embeddings should also disable core dumps if they are unable to upgrade. Note that core dumps are disabled by default but the wasm threads proposal (and shared memory) is enabled by default. It\u0027s recommended to upgrade to a patched version of Wasmtime, however.",
  "id": "GHSA-hc7m-r6v8-hg9q",
  "modified": "2025-11-13T22:02:14Z",
  "published": "2025-11-12T21:36:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hc7m-r6v8-hg9q"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-64345"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/commit/9ebb6934f00d58b92fb68ed0e0b16c0ae828ca10"
    },
    {
      "type": "WEB",
      "url": "https://docs.rs/wasmtime/latest/wasmtime/struct.Memory.html#method.new"
    },
    {
      "type": "WEB",
      "url": "https://docs.rs/wasmtime/latest/wasmtime/struct.SharedMemory.html#method.new"
    },
    {
      "type": "WEB",
      "url": "https://docs.wasmtime.dev/stability-release.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/bytecodealliance/wasmtime"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/releases/tag/v38.0.4"
    },
    {
      "type": "WEB",
      "url": "https://rustsec.org/advisories/RUSTSEC-2025-0118.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Wasmtime provides unsound API access to a WebAssembly shared linear memory"
}

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

CVE-2025-64345 (GCVE-0-2025-64345)

FKIE_CVE-2025-64345

GHSA-HC7M-R6V8-HG9Q

Impact

Patches

Workarounds

Tags

Sightings

Nomenclature