Vulnerability in Bytecodealliance Wasmtime
CVE-2026-34944
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.003 (15.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 15.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.000
Affected products
- Bytecodealliance Wasmtime — versions < 24.0.7, >= 25.0.0, < 36.0.7, >= 37.0.0, < 42.0.2
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-34944?
- CVE-2026-34944 is a medium-severity vulnerability in Bytecodealliance Wasmtime, classified under CWE-248. CVSS score: 5.7/10. Published 2026-04-09.
- How severe is CVE-2026-34944?
- Medium severity. CVSS v3 base score is 5.7 out of 10.