Vulnerability · Published Nov 12, 2025 · Assigned by GitHub_M
CVE-2025-64345Wasmtime provides unsound API access to a WebAssembly shared linear memory
Low 1.8
In plain English
A low-severity race condition in wasmtime from bytecodealliance. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | rust-wasmtime | no fix listed | DEBIAN-CVE-2025-64345 |
| Debian:14 | rust-wasmtime | 27.0.0+dfsg-2 | DEBIAN-CVE-2025-64345 |
| Ubuntu:24.04:LTS | rust-wasmtime | no fix listed | UBUNTU-CVE-2025-64345 |
| Ubuntu:25.10 | rust-wasmtime | no fix listed | UBUNTU-CVE-2025-64345 |
| Ubuntu:26.04:LTS | rust-wasmtime | no fix listed | UBUNTU-CVE-2025-64345 |
| Ubuntu:26.10 | rust-wasmtime | no fix listed | UBUNTU-CVE-2025-64345 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| bytecodealliance | wasmtime | >= 38.0.1, < 38.0.4>= 37.0.0, < 37.0.3>= 26.0.0, < 36.0.3< 24.0.5 |
Weakness: CWE-362 · Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N
References
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hc7m-r6v8-hg9q x_refsource_CONFIRM
- https://github.com/bytecodealliance/wasmtime/commit/9ebb6934f00d58b92fb68ed0e0b16c0ae828ca10 x_refsource_MISC
- https://docs.rs/wasmtime/latest/wasmtime/struct.Memory.html#method.new x_refsource_MISC
- https://docs.rs/wasmtime/latest/wasmtime/struct.SharedMemory.html#method.new x_refsource_MISC
- https://docs.wasmtime.dev/stability-release.html x_refsource_MISC
- https://github.com/bytecodealliance/wasmtime/releases/tag/v38.0.4 x_refsource_MISC