Server-side Request Forgery (SSRF) 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
- creditHem Parekh
Introduced: 27 Oct 2026
NewCVE-2026-116686 (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 Server-side Request Forgery (SSRF) via the _validate_tool_result function in src/mcp/client/session.py, where $ref references in a tool's output schema are resolved against external registries rather than being restricted to the schema document itself. An attacker who controls a tool's output schema can supply a $ref that points to an external or unresolvable URI, causing an unhandled Unresolvable exception that crashes the client session.