CVE-2026-24116 Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64

What is CVE-2026-24116?

CVE-2026-24116 is a medium-severity memory corruption vulnerability in bytecodealliance wasmtime, published on 27 Jan 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official 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.

Weakness: CWE-125

Which versions are affected by CVE-2026-24116?

7 open source packages ship an affected version, including wasmtime. It affects 1 product.

Products include Bytecodealliance Wasmtime.

How do I fix CVE-2026-24116?

Upgrade wasmtime to a fixed version for your release line: 36.0.5, 40.0.3 or 41.0.1.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-24116 being exploited?

There is no known exploitation of CVE-2026-24116 in the wild and no public exploit code.

Other vulnerabilities in bytecodealliance wasmtime

• CVE-2026-34971 Wasmtime miscompiled guest heap access enables sandbox escape on aarch64 Cranelift Critical 9.0
• CVE-2026-34987 Wasmtime with Winch compiler backend on aarch64 may allow a sandbox-escaping memory access Critical 9.0
• CVE-2022-39393 Wasmtime vulnerable to data leakage between instances in the pooling allocator High 8.6
• CVE-2022-24791 Use after free in Wasmtime High 8.1
• CVE-2026-47261 Wasmtime: WASI path_open(TRUNCATE) bypasses `FilePerms::WRITE` host restriction High 7.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-75533, AZL-75536, DEBIAN-CVE-2026-24116, GHSA-vc8c-j3xm-xj73, RUSTSEC-2026-0006, UBUNTU-CVE-2026-24116.