CVE-2026-14541: Authentication Bypass and Audience Confusion in MCP Toolbox OAuth Provider
Google · mcp-toolbox
Affected: Google mcp-toolbox · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 16% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- Google · mcp-toolbox1.4.0
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
CoverageNo articles yet
No CyberSIXT article names CVE-2026-14541 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.