CVE-2026-108699

Description

hyper-mcp through 0.8.3 contains an improper signature verification vulnerability that allows attackers to load malicious WebAssembly plugins because cosign_verify_args() accepts any signer identity and OIDC issuer by default. Attackers controlling a plugin image reference can sign a malicious image with a free Sigstore keyless certificate to execute plugins with configured host, filesystem, and environment capabilities.

References

• https://github.com/hyper-mcp-rs/hyper-mcp
• https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/config.rs#L138-L170
• https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs#L157-L190
• https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/hyper-mcp-oci-signature-manifest-toctou
• https://www.vulncheck.com/advisories/hyper-mcp-through-0.8.3-improper-signature-verification-of-oci-webassembly-plugins