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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
Vulnerable Products
hyper-mcp-rs:hyper-mcp
References 6
https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/hyper-mcp-oci-signature-manifest-toct…
NVD
https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs#L157-L190
NVD
https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/config.rs#L138-L170
NVD
https://github.com/hyper-mcp-rs/hyper-mcp
NVD
https://www.vulncheck.com/advisories/hyper-mcp-through-0.8.3-improper-signature…
VulnCheck Advisory: hyper-mcp through 0.8.3 Improper Signature Verification of OCI WebAssembly Plugins
https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/cve-2026-108698-108699-hyper-mcp-oci-…
134c704f-9b21-4f2e-91b3-4a467353bcc0