CVE-2026-59951

PyPI/mcp CVE-2026-59951: high 7.5

MCP Python SDK: Unbounded Session Accumulation in StreamableHTTP Transport Enables Resource Exhaustion

Action: Upgrade mcp to 1.30.0 or later.

pip install mcp==1.30.0

pip install mcp==2.2.0

Affected

Fixed versions

Sources

• osv: GHSA-84m7-p3x7-pcfv
• https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-84m7-p3x7-pcfv
• https://nvd.nist.gov/vuln/detail/CVE-2026-59951
• https://github.com/modelcontextprotocol/python-sdk/pull/3395
• https://github.com/modelcontextprotocol/python-sdk/pull/3426
• https://github.com/modelcontextprotocol/python-sdk/commit/92120b4b0f50385af096592d7cee932fc1d994e7
• https://github.com/modelcontextprotocol/python-sdk/commit/d2290ca3434731b68ea3e2270bc06a6e6575931b
• https://github.com/modelcontextprotocol/python-sdk
• https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.30.0
• https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.2.0

CVE-2026-59951 · published 2026-10-15T20:13:13Z · modified 2026-10-15T20:30:08.565001293Z · JSON