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Fencer Vulns
low 1.8

CVE-2025-64345 json

Wasmtime provides unsound API access to a WebAssembly shared linear memory

published 2025-11-11 11 mo ago modified 2026-10-18 21 d ago also EUVD-2025-131930 , GHSA-hc7m-r6v8-hg9q , JLSEC-2026-1350 , RUSTSEC-2025-0118

cvss
1.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

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.

Patch / fix

  • crates.io wasmtime 24.0.5, 36.0.3, 37.0.3, 38.0.4
  • julia Wasmtime_jll 39.0.0+0
  • bytecodealliance wasmtime 24.0.5, 36.0.3, 37.0.3, 38.0.4
  • rust-wasmtime Debian 14 27.0.0+dfsg-2

debian advisories DEBIAN-CVE-2025-64345

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-64345 updated cvss 1.8

wasmtime: Wasmtime unsound API access to shared linear memory

  • Red Hat Connectivity Link 1 rhcl-1/wasm-shim-rhel9
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
11 mo ago

Exploit prediction

0.12% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 1.8 CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N
GitHub 3.1 1.8 CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N
OSV 3.1 1.8 CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
crates.io wasmtime
>=38.0.0, <38.0.4
>=37.0.0, <37.0.3
>=26.0.0, <36.0.3
<24.0.5
>=0.0.0-0, <24.0.5
>=25.0.0, <36.0.3
38.0.4
37.0.3
36.0.3
24.0.5
julia Wasmtime_jll
<39.0.0+0
39.0.0+0

Affected products

  • bytecodealliance wasmtime

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.