CVE-2026-64651

Unauthorized host tool invocation via process-path fallback

Published Jul 20, 2026 · Updated Jul 20, 2026

Authorization bypass in Vercel @ai-sdk/harness-opencode 1.0.27 and earlier allows local users to invoke host-exposed tools. The tool relay treats any Linux process whose command line contains the host-tool-mcp.mjs helper path as authorized, without matching a model-authorized tool event. An active harness session with exposed host tools and untrusted sandbox code is required, after which the code can perform secret lookups, deployments, or cloud API calls.

CVSS severity6.3
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Vercel @ai-sdk/harness-opencode 1.0.27 and earlier allows local users to invoke host-exposed tools. The tool relay treats any Linux process whose command line contains the host-tool-mcp.mjs helper path as authorized, without matching a model-authorized tool event. An active harness session with exposed host tools and untrusted sandbox code is required, after which the code can perform secret lookups, deployments, or cloud API calls.

The record

CVE
CVE-2026-64651
Published
Jul 20, 2026
Updated
Jul 20, 2026
Vendor
Vercel
Product
@ai-sdk/harness-opencode
Classifications
T1068
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.0.29

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Vercel · @ai-sdk/harness-opencodeversion=< 1.0.29

Published CVSS scores

6.3GitHubCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:H/SI:H/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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