CVE-2026-14541Authentication Bypass and Audience Confusion in MCP Toolbox OAuth Provider
Updated under an hour ago ()
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It affects Google mcp-toolbox and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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An authentication bypass and audience confusion vulnerability exists in the Google OAuth provider component of Google mcp-toolbox version 1.4.0. When a Google authService is initialized with mcpEnabled: true but lacks an explicitly defined audience or clientId, the ValidateMCPAuth pipeline for opaque tokens skips audience validation entirely. As a result, the toolbox will accept any valid Google OAuth access token—even those minted for unrelated ecosystem applications—granting unauthorized clients access to protected tools and data backends.
- CVSS
- 8.0 HIGH (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U
- Weakness (CWE)
- CWE-287
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- NVD analysis
- Analyzed
- Record last updated
- Jul 31, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Google mcp-toolbox google:mcp_toolbox (from the name) | 1.4.0 | CNA record |
google mcp_toolbox_for_databases google:mcp_toolbox_for_databases | 1.4.0 | NVD |
References
- https://github.com/googleapis/mcp-toolbox/pull/3450issue-tracking, patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.