The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). From 1.8.0 until 1.30.0 and 2.2.0, stateful Streamable HTTP servers, including FastMCP, MCPServer, Server.streamable_http_app(), and StreamableHTTPSessionManager, retain session entries without an idle expiration or aggregate session-count limit. DELETE, refused opening requests, and completed sessions do not reliably discard their entries, and each entry can retain parsed initialize parameters. A client that can reach the endpoint can therefore create ordinary short requests that grow server memory without bound until restart. Stateless HTTP, stdio, and SSE transports are not affected. This issue is fixed in versions 1.30.0 and 2.2.0.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP).
    From 1.8.0 until 1.30.0 and 2.2.0, stateful Streamable HTTP servers, including FastMCP, MCPServer,
    Server.streamable_http_app(), and StreamableHTTPSessionManager, retain session entries without an idle
    expiration or aggregate session-count limit. DELETE, refused opening requests, and completed sessions do
    not reliably discard their entries, and each entry can retain parsed initialize parameters. A client that
    can reach the endpoint can therefore create ordinary short requests that grow server memory without bound
    until restart. Stateless HTTP, stdio, and SSE transports are not affected. This issue is fixed in versions
    1.30.0 and 2.2.0. (CVE-2026-59951)

ID	Name	Product	Family	Type	Severity
476119	Chainguard: multiple open-webui packages: security update to 0.12.3-r1	Tenable Cloud Security	Chainguard Local Security Checks	Local	medium
476119	Chainguard: multiple open-webui packages: security update to 0.12.3-r1	Tenable Self-Hosted Container Security	Chainguard Local Security Checks	Local	medium
474708	SCA: security update for mcp (GHSA-84m7-p3x7-pcfv)	Tenable Cloud Security	SCA Checks	Local	medium
474708	SCA: security update for mcp (GHSA-84m7-p3x7-pcfv)	Tenable Self-Hosted Container Security	SCA Checks	Local	medium

Detections

Analytics

CVE-2026-59951

medium

Tenable Plugins

medium

medium

medium

medium