CVE-2026-108699: high-severity vulnerability in hyper-mcp-rs hyper-mcp
hyper-mcp through 0.8.3 Improper Signature Verification of OCI WebAssembly Plugins
Published · Updated
41Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 8.3epss 0.1%
exploitation probability
0.1%top 97% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
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.
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
Affected products
hyper-mcp-rs · hyper-mcppublic PoCs found — 1
cve_referencehackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/cve-2026-108698-108699-hyper-mcp-oci-signature-manifest-toctouunverified⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
Related CVEs — hyper-mcp-rs hyper-mcp
In the same product, most dangerous first.
References
https://github.com/hyper-mcp-rs/hyper-mcphttps://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/config.rs#L138-L170https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs#L157-L190https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/cve-2026-108698-108699-hyper-mcp-oci-signature-manifest-toctouhttps://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/hyper-mcp-oci-signature-manifest-toctouhttps://www.vulncheck.com/advisories/hyper-mcp-through-0.8.3-improper-signature-verification-of-oci-webassembly-plugins