CVE-2025-64345

Wasmtime provides unsound API access to a WebAssembly shared linear memory

State
Published
Severity
1.8 Low
Published
Nov 12, 2025
Updated
Nov 12, 2025
Reserved
Oct 30, 2025

Read the record on cve.org

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.

Scores

CVSSScoreVectorSource
3.11.8 LowCVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:NGitHub_M

Weaknesses

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

Affected Products

ProductVersions
wasmtimebytecodealliance
  • >= 38.0.1, < 38.0.4Affected
  • >= 37.0.0, < 37.0.3Affected
  • >= 26.0.0, < 36.0.3Affected
  • < 24.0.5Affected

References

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