CVE-2026-108699 hyper-mcp through 0.8.3 Improper Signature Verification of OCI WebAssembly Plugins
Attackers can execute malicious WebAssembly plugins by bypassing signature verification in hyper-mcp, leading to arbitrary code execution with host capabilities.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-108699?
CVE-2026-108699 is a high-severity vulnerability in hyper-mcp-rs hyper-mcp, published on 11 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-347
Which versions are affected by CVE-2026-108699?
How do I fix CVE-2026-108699?
No fix has been published for CVE-2026-108699 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-108699 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-108699 exists.
Sources
Also known as GHSA-4j25-h357-wg62.