CVE-2026-108698
Received Received - Intake

Signature Verification Bypass in hyper-mcp WebAssembly Plugin Loading

Publication date: 2026-10-11

Last updated on: 2026-10-11

Assigner: VulnCheck

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.

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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-2026-108698
EUVD
EUVD-2026-96998

Affected Vendors & Products

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

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-367 The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

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Executive Summary

This vulnerability in hyper-mcp through 0.8.3 allows attackers to bypass signature verification by serving an unsigned malicious manifest to the loader while providing a signed one to Cosign. The issue occurs in the load_wasm function in src/wasm/oci.rs, where the system verifies the Cosign signature of a separately resolved tag instead of the loaded manifest itself.

Detection Guidance

To detect this vulnerability, inspect hyper-mcp versions and check for OCI registry interactions. Verify if Cosign signature verification is properly bound to resolved manifests. Monitor for unsigned WASM plugins being loaded despite Cosign checks. Review logs for mismatches between resolved tags and verified manifests.

Impact Analysis

Attackers exploiting this vulnerability could execute unsigned WebAssembly plugins with configured host capabilities, potentially leading to unauthorized code execution, data breaches, or system compromise if the plugins have elevated permissions.

Compliance Impact

This vulnerability could lead to unauthorized execution of WebAssembly plugins, potentially violating data integrity and confidentiality requirements in GDPR and HIPAA. Unsigned malicious plugins might access or exfiltrate sensitive data, undermining compliance with these regulations.

Mitigation Strategies

Update hyper-mcp to a version that fixes the signature verification bypass in load_wasm. Avoid using unsigned WebAssembly plugins with host capabilities. Monitor registry responses for discrepancies between signed and unsigned manifests.

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