Incorrect Authorization Affecting mcp package, versions [1.10.0,1.30.0)[2.0.0,2.2.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published27 Oct 2026
- disclosed27 Oct 2026
- creditUnknown
Introduced: 27 Oct 2026
NewCVE-2026-116684 (opens in a new tab)How to fix?
Upgrade mcp to version 1.30.0, 2.2.0 or higher.
Overview
mcp is a Model Context Protocol SDK
Affected versions of this package are vulnerable to Incorrect Authorization via the BearerAuthBackend middleware, which fails to validate the resource indicator (RFC 8707 audience) of incoming bearer tokens against the server's own resource_server_url. An attacker in possession of a valid token issued for a different resource server can present that token and gain unauthorized access, bypassing the intended audience restriction.
Note: This is only exploitable if the validate_token_resource option is explicitly set to True in AuthSettings - upgrading alone does not enable the check, as the new setting defaults to off.