CVE-2026-108699
hyper-mcp through 0.8.3 Improper Signature Verification of OCI WebAssembly Plugins
- State
- Published
- Severity
- 8.3 High
- Published
- Oct 11, 2026
- Updated
- Oct 13, 2026
- Reserved
- Oct 10, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.3 High | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 6.5 Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N | VulnCheck |
Weaknesses
- CWE-347 Improper Verification of Cryptographic Signature
Affected Products
| Product | Versions |
|---|---|
hyper-mcphyper-mcp-rs |
|
References
- https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/hyper-mcp-oci-signature-manifest-toctouthird-party-advisory
- https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs#L157-L190technical-description
- https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/config.rs#L138-L170technical-description
- https://github.com/hyper-mcp-rs/hyper-mcpproduct
- VulnCheck Advisory: hyper-mcp through 0.8.3 Improper Signature Verification of OCI WebAssembly Pluginsthird-party-advisory
- https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/cve-2026-108698-108699-hyper-mcp-oci-signature-manifest-toctouexploit
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