CVE-2026-34944: Bytecodealliance Wasmtime

Medium severity, CVSS 5.7. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Bytecodealliance Wasmtime: before 24.0.7 (fixed in 24.0.7); from 25.0.0, before 36.0.7 (fixed in 36.0.7); from 37.0.0, before 42.0.2 (fixed in 42.0.2); from 43.0.0, before 43.0.1 (fixed in 43.0.1)

Published 2026-04-09. Last modified 2026-06-17.