CVE-2026-47218: Insecure Deserialization

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.

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Weakness Type (CWE)

CWE-502 Deserialization of Untrusted Data

References

Other References

https://github.com/containerd/runwasi/commit/d28ab73c2c8a6c50d1927078821bd418b9e51638 https://github.com/containerd/runwasi/releases/tag/containerd-shim-wasmtime/v0.6.1 https://github.com/containerd/runwasi/security/advisories/GHSA-cc25-vq59-rcjx

Frequently Asked Questions

What is CVE-2026-47218? +

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.

How do I check if I'm vulnerable to CVE-2026-47218? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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