CVE-2026-108699
Received Received - Intake

Improper Signature Verification in hyper-mcp

Publication date: 2026-10-11

Last updated on: 2026-10-11

Assigner: VulnCheck

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.

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Meta Information

Published
2026-10-11
Last Modified
2026-10-11
Generated
2026-10-11
AI Q&A
2026-10-11
EPSS Evaluated
N/A
NVD
CVE-2026-108699
EUVD
EUVD-2026-96999

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
hyper-mcp-rs hyper-mcp 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-347 The product does not verify, or incorrectly verifies, the cryptographic signature for data.

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Executive Summary

hyper-mcp through 0.8.3 has an improper signature verification flaw where cosign_verify_args() accepts any signer identity and OIDC issuer by default. This lets attackers load malicious WebAssembly plugins by signing a malicious image with a free Sigstore keyless certificate.

Detection Guidance

To detect this vulnerability, check if you are running hyper-mcp version 0.8.3 or earlier. Use commands like 'hyper-mcp --version' or inspect package metadata. Review logs for unsigned or maliciously signed WebAssembly plugins loaded via OCI registries.

Impact Analysis

Attackers controlling a plugin image reference can execute plugins with host, filesystem, and environment capabilities. This could lead to unauthorized code execution, data theft, or system compromise depending on the plugin's configured permissions.

Compliance Impact

This vulnerability could violate compliance requirements by enabling unauthorized access to sensitive data or systems. GDPR may require breach notification, while HIPAA could involve unauthorized access to protected health information, leading to penalties or legal consequences.

Mitigation Strategies

Update hyper-mcp to a version that enforces strict signer identity and OIDC issuer verification. Review and restrict plugin image references to trusted sources. Monitor for unauthorized WebAssembly plugin execution.

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