CVE-2026-108699
hyper-mcp through 0.8.3 Improper Signature Verification of OCI WebAssembly Plugins
hyper-mcp-rs hyper-mcp
CVSS
8.3HighExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 13 Oct 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.13%Chance of exploitation activity in the next 30 days, higher than 2% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
What fixes it
No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.
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.
Text from CVE List
Affected versions 1
- hyper-mcpaffected: all versions through 0.8.3CVE List
References 6
- hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/hyper-mcp-oci-signature-manifest-toctouAdvisoryvia CVE List
- vulncheck.com/advisories/hyper-mcp-through-0.8.3-improper-signature-verification-of-oci-webassembly-pluginsAdvisoryvia CVE List
- hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/cve-2026-108698-108699-hyper-mcp-oci-signature-manifest-toctouExploitvia CVE List
- github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs#L157-L190Referencevia CVE List
- github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/config.rs#L138-L170Referencevia CVE List
- github.com/hyper-mcp-rs/hyper-mcpReferencevia CVE List