CVE-2026-34944

MEDIUM

Wasmtime segfault or unused out-of-sandbox load with `f64x2.splat` operator on x86-64

Title source: cna
STIX 2.1

Description

Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, On x86-64 platforms with SSE3 disabled Wasmtime's compilation of the f64x2.splat WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it's possible for out-of-sandbox data to be loaded, but this data is not visible to WebAssembly guests. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.

References (1)

Core 1
Core References

Scores

CVSS v3 5.7
EPSS 0.0023
EPSS Percentile 13.3%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-248
Status published
Products (5)
bytecodealliance/wasmtime < 24.0.7 (2 CPE variants)
bytecodealliance/wasmtime >= 25.0.0, < 36.0.7
bytecodealliance/wasmtime >= 37.0.0, < 42.0.2
bytecodealliance/wasmtime >= 43.0.0, < 44.0.1
crates.io/wasmtime 0 - 24.0.7crates.io
Published Apr 09, 2026
Tracked Since Apr 10, 2026