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.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-hc7m-r6v8-hg9q Wasmtime provides unsound API access to a WebAssembly shared linear memory
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 13 Nov 2025 10:00:00 +0000

Type Values Removed Values Added
First Time appeared Bytecodealliance
Bytecodealliance wasmtime
Vendors & Products Bytecodealliance
Bytecodealliance wasmtime

Wed, 12 Nov 2025 22:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 12 Nov 2025 21:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Wasmtime provides unsound API access to a WebAssembly shared linear memory
Weaknesses CWE-362
References
Metrics cvssV3_1

{'score': 1.8, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-11-12T21:40:37.909Z

Reserved: 2025-10-30T17:40:52.031Z

Link: CVE-2025-64345

cve-icon Vulnrichment

Updated: 2025-11-12T21:40:34.331Z

cve-icon NVD

Status : Received

Published: 2025-11-12T22:15:49.623

Modified: 2025-11-12T22:15:49.623

Link: CVE-2025-64345

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2025-11-13T09:52:22Z