CVE-2026-108698 hyper-mcp-rs CVE debrief

Who should care

Defenders responsible for securing WebAssembly plugins and ensuring the integrity of the hyper-mcp system should be aware of this vulnerability and take steps to verify the integrity of plugins and ensure that only signed plugins are executed.

Why it matters

Defenders should prioritize verifying the integrity of WebAssembly plugins and ensuring that only signed plugins are executed due to a signature verification bypass vulnerability in hyper-mcp through 0.8.3.

• Potential execution of unsigned WebAssembly plugins with configured host capabilities
• Bypass of signature verification for WebAssembly plugins
• Possible exploitation by attackers controlling registry responses
• Need for verification of plugin integrity and signature

Technical summary

The load_wasm function in src/wasm/oci.rs verifies the Cosign signature of a separately resolved tag rather than the loaded manifest. This allows attackers controlling registry responses for the tag to serve an unsigned malicious manifest to the loader and a signed one to Cosign, potentially executing unsigned WebAssembly plugins with configured host capabilities. Affected product deployments should be identified and verified for exposure. Defenders should prioritize verifying the integrity of WebAssembly plugins and ensuring that only signed plugins are executed.

Defensive priority

Defenders should prioritize verifying the integrity of WebAssembly plugins and ensuring that only signed plugins are executed. This may involve updating hyper-mcp to a version that correctly verifies the signature of the loaded manifest.

Recommended defensive actions

• Verify the integrity of WebAssembly plugins
• Ensure that only signed plugins are executed
• Update hyper-mcp to a version that correctly verifies the signature of the loaded manifest
• Monitor for potential exploitation attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and source item provide details about the vulnerability, including its description, affected versions, and references to additional information. However, the corpus does not establish versions beyond 0.8.3, exploitation, impact, or remediation, which require verification from the supplied official sources.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.