Low severity · published Nov 12, 2025
CVE-2025-64345
Wasmtime provides unsound API access to a WebAssembly shared linear memory
1.8
CVSS
0.1%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N
Attack vector
Local
Complexity
High
Privileges
High
User interaction
Required
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 2% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
WA
wasmtime · bytecodealliance
>= 38.0.1, < 38.0.4; >= 37.0.0, < 37.0.3; >= 26.0.0, < 36.0.3; < 24.0.5 · source: vendor
Affected product
WA
wasmtime
bytecodealliance
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