# CVE-2026-47218: runwasi: Forged Wasmtime precompiled OCI layer bypasses runwasi WASI sandbox

> Attackers can execute native code by forging Wasmtime precompiled OCI layers, bypassing the WASI sandbox in containerd runwasi shims.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-cc25-vq59-rcjx

## What is CVE-2026-47218?

CVE-2026-47218 is a critical unsafe deserialization vulnerability in containerd runwasi, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

runwasi facilitates running Wasm and WASI workloads managed by containerd. Prior to 0.6.1, containerd-shim-wasmtime-v1 can treat Wasmtime precompiled bytes supplied directly in an OCI image layer as a trusted artifact from the precompile-cache path and deserialize them as native code. An attacker who causes a victim to run a crafted image can bypass WebAssembly validation and execute native code in the shim zygote process, gaining the filesystem, environment, credentials, networking, and Linux syscall access available to the workload container. Downstream shims built with runwasi's containerd-shim-wasm precompile-cache API are also affected if they implement Compiler and trust executable precompiled artifacts from OCI image layers; the 0.6.1 boundary applies specifically to containerd-shim-wasmtime and does not independently certify downstream product releases. The flaw escapes the WASI sandbox to the workload container boundary, but it does not by itself bypass container isolation or provide direct host code execution. This issue is fixed in version 0.6.1.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-47218?


## How do I fix CVE-2026-47218?

No fix has been published for CVE-2026-47218 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-47218 being exploited?

There is no known exploitation of CVE-2026-47218 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-47218 and fix it if it is affected.

What it is: CVE-2026-47218 is a critical unsafe deserialization vulnerability in containerd runwasi, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-47218 in the wild and no public exploit code.

Affected product: containerd runwasi. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-47218/ (Markdown: https://insights.sbomify.com/CVE-2026-47218/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-47218
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-47218
- OSV: https://osv.dev/vulnerability/CVE-2026-47218

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-47218/
Summaries are generated and may contain mistakes; the official description above is the record.