# CVE-2026-64651: AI SDK OpenCode Harness Tool Relay Authorization Bypass

> CVE-2026-64651: AI SDK OpenCode Harness Tool Relay Authorization Bypass. CVSS 6.3 (CVSS 4.0).

Canonical: https://rewindex.com/cve/CVE-2026-64651
Last updated: 2026-10-24T20:10:00Z

- Published: 2026-07-20 20:26 UTC · Updated: 2026-10-24 20:10 UTC · Assigner: GitHub\_M
- CVSS: 6.3 (CVSS 4.0) · Severity: Medium
- EPSS: 0.17%, 7th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-863

## Description

The \`@ai-sdk/harness-opencode\` tool connects HarnessAgent to OpenCode through a sandboxed bridge. Prior to version 1.0.28, the tool relay authorizes requests from any process whose command line contains an allowed helper script path (\`host-tool-mcp.mjs\`). This allows untrusted code executing in the sandbox to invoke arbitrary host-exposed tools including secret lookups, deployment operations, and cloud API calls without a corresponding model-authorized tool-call event. Exploitation requires a Linux environment (the vulnerable fallback checks \`process.platform === 'linux'\` and reads \`/proc\`); an active harness session with one or more host-provided tools; and untrusted code executing in the sandbox (e.g. a malicious dependency, build script, or lifecycle hook) The fix in version 1.0.28 removes the process-path authorization fallback entirely. Relay requests are now only accepted after exact, short-lived, one-time authorization matching the tool name and input from a bridge-observed model event. Some workarounds are available. Do not run the OpenCode harness on untrusted repositories or with untrusted dependencies, and/or limit host-exposed tools to non-sensitive operations when working with untrusted code.

## Affected vendors and products

- vercel: @ai-sdk/harness-opencode

## Tracked companies

- [Vercel](https://rewindex.com/company/vercel.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-64651)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-64651)
- [https://github.com/vercel/ai/pull/17105](https://github.com/vercel/ai/pull/17105)
- [https://github.com/vercel/ai/security/advisories/GHSA-g48p-5rr5-8rgq](https://github.com/vercel/ai/security/advisories/GHSA-g48p-5rr5-8rgq)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-64651 · Markdown: https://rewindex.com/cve/CVE-2026-64651.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-64651 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:11:24.128Z