CVE-2026-108698
hyper-mcp through 0.8.3 OCI Plugin Signature Verification TOCTOU Race Condition
- 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 a signature verification bypass vulnerability in load_wasm in src/wasm/oci.rs that verifies the Cosign signature of a separately resolved tag rather than the loaded manifest. Attackers controlling registry responses for the tag can serve an unsigned malicious manifest to the loader and a signed one to Cosign, executing unsigned WebAssembly plugins with configured host 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-367 Time-of-check Time-of-use (TOCTOU) Race Condition
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#L79-L148technical-description
- https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs#L193-L224technical-description
- https://github.com/hyper-mcp-rs/hyper-mcpproduct
- VulnCheck Advisory: hyper-mcp through 0.8.3 OCI Plugin Signature Verification TOCTOU Race Conditionthird-party-advisory
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