# CVE-2026-24116: Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64 > Wasmtime may crash or leak out-of-sandbox data on x86-64 with AVX when signals-based traps are disabled, requiring an upgrade. - **Severity:** Medium 4.1 (`CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** A user has to click or open something - **Fix available:** Yes - **Published:** 27 Jan 2026 - **Updated:** 27 Jan 2026 - **Also known as:** AZL-75533, AZL-75536, DEBIAN-CVE-2026-24116, GHSA-vc8c-j3xm-xj73, RUSTSEC-2026-0006, UBUNTU-CVE-2026-24116 ## 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 (Out-of-bounds Read) ## Which versions are affected by CVE-2026-24116? 7 open source packages ship an affected version, including wasmtime. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `wasmtime` | crates.io | From 29.0.0 | 36.0.5, 40.0.3, 41.0.1 | | `wasmtime` | crates.io | From 29.0.0 | 36.0.5 | | `wasmtime` | crates.io | From 29.0.0 | 36.0.5 | | `wasmtime` | crates.io | From 37.0.0 | 40.0.3 | | `wasmtime` | crates.io | From 37.0.0 | 40.0.3 | | `wasmtime` | crates.io | From 41.0.0 | 41.0.1 | | `wasmtime` | crates.io | From 41.0.0 | 41.0.1 | Products: 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. ## 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](https://insights.sbomify.com/CVE-2026-34971/): Wasmtime miscompiled guest heap access enables sandbox escape on aarch64 Cranelift (critical 9.0) - [CVE-2026-34987](https://insights.sbomify.com/CVE-2026-34987/): Wasmtime with Winch compiler backend on aarch64 may allow a sandbox-escaping memory access (critical 9.0) - [CVE-2022-39393](https://insights.sbomify.com/CVE-2022-39393/): Wasmtime vulnerable to data leakage between instances in the pooling allocator (high 8.6) - [CVE-2022-24791](https://insights.sbomify.com/CVE-2022-24791/): Use after free in Wasmtime (high 8.1) - [CVE-2026-47261](https://insights.sbomify.com/CVE-2026-47261/): Wasmtime: WASI path_open(TRUNCATE) bypasses `FilePerms::WRITE` host restriction (high 7.5) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-24116 and fix it if it is affected. What it is: 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. Exploitation: There is no known exploitation of CVE-2026-24116 in the wild and no public exploit code. Affected packages and fixed versions: - wasmtime (crates.io): affected from 29.0.0; fixed in 36.0.5, 40.0.3, 41.0.1 - wasmtime (crates.io): affected from 29.0.0; fixed in 36.0.5 - wasmtime (crates.io): affected from 29.0.0; fixed in 36.0.5 - wasmtime (crates.io): affected from 37.0.0; fixed in 40.0.3 - wasmtime (crates.io): affected from 37.0.0; fixed in 40.0.3 - wasmtime (crates.io): affected from 41.0.0; fixed in 41.0.1 - wasmtime (crates.io): affected from 41.0.0; fixed in 41.0.1 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-24116/ (Markdown: https://insights.sbomify.com/CVE-2026-24116/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-24116 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-24116 - OSV: https://osv.dev/vulnerability/CVE-2026-24116 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-24116/ Summaries are generated and may contain mistakes; the official description above is the record.