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

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

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.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2026-47218 being exploited?

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

Sources

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

Also known as GHSA-cc25-vq59-rcjx.