# CVE-2022-39394: wasmtime_trap_code C API function has out of bounds write vulnerability

> A memory corruption vulnerability in the Wasmtime C API allows out-of-bounds writes, potentially leading to code execution or crashes.

- **Severity:** Low 3.8 (`CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 10 Nov 2022
- **Updated:** 23 Apr 2025
- **Also known as:** GHSA-h84q-m8rr-3v9q, RUSTSEC-2022-0097, UBUNTU-CVE-2022-39394

## What is CVE-2022-39394?

CVE-2022-39394 is a low-severity memory corruption vulnerability in bytecodealliance wasmtime, published on 10 Nov 2022. 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 standalone runtime for WebAssembly. Prior to version 2.0.2, there is a bug in Wasmtime's C API implementation where the definition of the `wasmtime_trap_code` does not match its declared signature in the `wasmtime/trap.h` header file. This discrepancy causes the function implementation to perform a 4-byte write into a 1-byte buffer provided by the caller. This can lead to three zero bytes being written beyond the 1-byte location provided by the caller. This bug has been patched and users should upgrade to Wasmtime 2.0.2. This bug can be worked around by providing a 4-byte buffer casted to a 1-byte buffer when calling `wasmtime_trap_code`. Users of the `wasmtime` crate are not affected by this issue, only users of the C API function `wasmtime_trap_code` are affected.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2022-39394?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `wasmtime` | crates.io | All versions | 1.0.2 |
| `wasmtime` | crates.io | All versions | 1.0.2 |
| `wasmtime` | crates.io | From 0.0.0-0 | 1.0.2, 2.0.2 |
| `wasmtime` | crates.io | From 2.0.0 | 2.0.2 |
| `wasmtime` | crates.io | From 2.0.0 | 2.0.2 |

Products: Bytecodealliance Wasmtime.

## How do I fix CVE-2022-39394?

Upgrade wasmtime to a fixed version for your release line: 1.0.2 or 2.0.2.

## Is CVE-2022-39394 being exploited?

There is no known exploitation of CVE-2022-39394 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-2022-39394 and fix it if it is affected.

What it is: CVE-2022-39394 is a low-severity memory corruption vulnerability in bytecodealliance wasmtime, published on 10 Nov 2022. 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-2022-39394 in the wild and no public exploit code.

Affected packages and fixed versions:
- wasmtime (crates.io): affected all versions; fixed in 1.0.2
- wasmtime (crates.io): affected all versions; fixed in 1.0.2
- wasmtime (crates.io): affected from 0.0.0-0; fixed in 1.0.2, 2.0.2
- wasmtime (crates.io): affected from 2.0.0; fixed in 2.0.2
- wasmtime (crates.io): affected from 2.0.0; fixed in 2.0.2

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-2022-39394/ (Markdown: https://insights.sbomify.com/CVE-2022-39394/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-39394
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-39394
- OSV: https://osv.dev/vulnerability/CVE-2022-39394

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-39394/
Summaries are generated and may contain mistakes; the official description above is the record.