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OpenAdvisories
Medium · 4.1 CVE-2026-24116 EUVD-2026-4773GHSA-vc8c-j3xm-xj73RUSTSEC-2026-0006

Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64

Published Jan 27, 2026 · Updated Jan 27, 2026 · Assigned by GitHub_M

Description

Wasmtime is a runtime for WebAssembly. Starting in version 29.0.0 and prior to version 36.0.5, 40.0.3, and 41.0.1, on x86-64 platforms with AVX, Wasmtime's compilation of the `f64.copysign` 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 unless there is another bug in Cranelift this data is not visible to WebAssembly guests. Wasmtime 36.0.5, 40.0.3, and 41.0.1 have been released to fix this issue. Users are recommended to upgrade to the patched versions of Wasmtime. Other affected versions are not patched and users should updated to supported major version instead. This bug can be worked around by enabling signals-based-traps. While disabling guard pages can be a quick fix in some situations, it's not recommended to disabled guard pages as it is a key defense-in-depth measure of Wasmtime.

Affected products

VendorProductAffectedFixed
bytecodealliance wasmtime >= 29.0.0, < 36.0.5, >= 37.0.0, < 40.0.3, = 41.0.0 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 rust-wasmtime 36.0.5+dfsg-1 —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 rust-wasmtime No fix yet —
Ubuntu 26.04 LTS rust-wasmtime No fix yet —
Ubuntu 25.10 rust-wasmtime No fix yet —
Ubuntu 24.04 LTS rust-wasmtime No fix yet —

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 rust 1.75.0-25 —

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling wasmcloud 2.0.1-r0 —
Wolfi rolling wizer 10.0.0-r4 —
Wolfi rolling yara-x 1.12.0-r1 —
Wolfi rolling zed 0.228.0-r3 —
Wolfi rolling zellij 0.44.0-r0 —

Affected packages

EcosystemPackageAffectedFixedRecord
crates.io wasmtime >= 29.0.0, < 36.0.5 36.0.5 GHSA-vc8c-j3xm-xj73
crates.io wasmtime >= 37.0.0, < 40.0.3 40.0.3 GHSA-vc8c-j3xm-xj73
crates.io wasmtime >= 41.0.0, < 41.0.1 41.0.1 GHSA-vc8c-j3xm-xj73
crates.io wasmtime >= 29.0.0, < 36.0.5 · >= 37.0.0, < 40.0.3 · >= 41.0.0, < 41.0.1 36.0.5, 40.0.3, 41.0.1 RUSTSEC-2026-0006

References