https://cve.radiocsirt.org/rss/recent/all/10 Most recent entries from all 2026-10-02T20:06:04.763872+00:00 Vulnerability-Lookup csirt@opendfir.org python-feedgen Contains only the most 10 recent entries. https://cve.radiocsirt.org/vuln/cve-2026-34944 CVE-2026-34944 — Wasmtime segfault or unused out-of-sandbox load with `f64x2.splat` operator on x86-64 2026-10-02T20:06:04.765570+00:00

Affected: bytecodealliance wasmtime

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.

 https://cve.radiocsirt.org/vuln/ghsa-qqfj-4vcm-26hv GHSA-qqfj-4vcm-26hv — Wasmtime segfault or unused out-of-sandbox load with `f64x2.splat` operator on x86-64 2026-10-02T20:06:04.765624+00:00

Affected: crates.io: wasmtime

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](https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.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.

### Details

The `f64x2.splat` operator, when operating on a value loaded from a memory (for example with f64.load), compiles with Cranelift to code on x86-64 without SSE3 that loads 128 bits (16 bytes) rather than the expected 64 bits (8 bytes) from memory. When the address is in-bounds for a (correct) 8-byte load but not an (incorrect) 16-byte load, this can load beyond memory by up to 8 bytes. This can result in three different behaviors depending on Wasmtime's configuration:

1. If guard pages are disabled then this extra data will be loaded. The extra data is present in the upper bits of a register, but the upper bits are not visible to WebAssembly guests. Actually witnessing this data would require a different bug in Cranelift, of which none are known. Thus in this situation while it's something we're patching in Cranelift it's not a security issue. 2. If guard pages are enabled, and [signals-based-traps](https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.sig…