CVE-2026-108698
CVE-2026-108698
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.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
Published .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Weakness classification (CWE)
References
- hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/hyper-mcp-oci-signature-manifest-toctou (third-party-advisory)
- github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs (technical-description)
- github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs (technical-description)
- github.com/hyper-mcp-rs/hyper-mcp (product)
- www.vulncheck.com/advisories/hyper-mcp-through-0.8.3-oci-plugin-signature-verif… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-108698?
- CVE-2026-108698 is a medium-severity vulnerability, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 6.5/10. Published 2026-10-11.
- How severe is CVE-2026-108698?
- Medium severity. CVSS v3 base score is 6.5 out of 10.