Read the docs
TI-2026-74320 Aliases CVE-2026-59951GHSA-84m7-p3x7-pcfv

Unbounded sessions in MCP Python SDK StreamableHTTP transport

Priority LOW 37CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · Low
Fix status
Partial Red Hat: 4 fixed, 11 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

The MCP Python SDK (mcp on PyPI) from 1.8.0 before 1.30.0 and from 2.0.0 before 2.2.0 keeps session entries in stateful Streamable HTTP servers without idle expiration or a session-count limit. Entries are not reliably discarded after DELETE requests, refused requests or completed sessions (CWE-770). A client that can reach the endpoint can send ordinary short requests until server memory grows without bound and the server must be restarted.

Written with Claude Haiku 5.5 from the sources below · 2026-11-04

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00458 39th percentileScored 2026-11-08
Fix Partial python-sdk (modelcontextprotocol): 1.30.0, 2.2.0mcp (PyPI): 1.30.0, 2.2.0Red Hat: 8 advisoriesRed Hat: 4 fixed, 11 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MLflowpython-sdk1.8.0 to before 1.30.0; 2.0.0 to before 2.2.01.30.0, 2.2.0Patch availableCNA
—mcp (PyPI)1.8.0 to before 1.30.01.30.0Patch availableGHSA-84m7-p3x7-pcfv
—mcp (PyPI)2.0.0 to before 2.2.02.2.0Patch availableGHSA-84m7-p3x7-pcfv
  • python-sdk VendorMLflow Affected 1.8.0 to before 1.30.0; 2.0.0 to before 2.2.0 Fixed in 1.30.0, 2.2.0 Patch available CNA
  • mcp (PyPI) Vendor— Affected 1.8.0 to before 1.30.0 Fixed in 1.30.0 Patch available GHSA-84m7-p3x7-pcfv
  • mcp (PyPI) Vendor— Affected 2.0.0 to before 2.2.0 Fixed in 2.2.0 Patch available GHSA-84m7-p3x7-pcfv

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:*——MLflow
  • cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:* Versions — — ·MLflow

Remediation

Upgrade the mcp package to 1.30.0 (1.x line) or 2.2.0 (2.x line). Red Hat fixes are in Red Hat AI Inference Server 3.5 (RHSA-2026:94738, RHSA-2026:94721, RHSA-2026:94717, RHSA-2026:94709, RHSA-2026:94702), Red Hat OpenShift AI 3.4 (RHSA-2026:92510), and Red Hat Satellite 6.18 and 6.19 (RHSA-2026:92667, RHSA-2026:92666). The sources list no fixed version for Red Hat OpenShift AI (RHOAI). The sources list no fixed version for Red Hat Enterprise Linux AI (RHEL AI) 3.

Written with Claude Haiku 5.5 from the sources below · 2026-11-04

  • Fix · CNA python-sdk (modelcontextprotocol) Fixed in 1.30.0, 2.2.0
  • Fix · GHSA-84m7-p3x7-pcfv mcp (PyPI) Fixed in 1.30.0 Advisory →
  • Fix · GHSA-84m7-p3x7-pcfv mcp (PyPI) Fixed in 2.2.0 Advisory →

Red Hat 8 advisories

  • RHSA-2026:94738 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference 3.5.3 (CUDA)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-cuda-rhel9
  • RHSA-2026:94721 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference Tech Preview 3.5.3 (Gaudi)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-gaudi-rhel9
  • RHSA-2026:94717 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference 3.5.3 (Spyre)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-spyre-rhel9
Show 5 more Red Hat advisories
  • RHSA-2026:94709 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference 3.5.3 (ROCm)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-rocm-rhel9
  • RHSA-2026:94702 Released 2026-11-03 · Red Hat rating Critical
    Red Hat AI Inference 3.5.3 (CPU)
    • Red Hat AI Inference Server 3.5 registry.redhat.io/rhaii/vllm-cpu-rhel9
  • RHSA-2026:92667 Released 2026-10-29 · Red Hat rating Critical
    satellite/foreman-mcp-server-rhel9 container image available as a Technology Preview
    • Red Hat Satellite 6.18 registry.redhat.io/satellite/foreman-mcp-server-rhel9
  • RHSA-2026:92666 Released 2026-10-29 · Red Hat rating Critical
    satellite/foreman-mcp-server-rhel9 container image available as a Technology Preview
    • Red Hat Satellite 6.19 registry.redhat.io/satellite/foreman-mcp-server-rhel9
  • RHSA-2026:92510 Released 2026-10-29 · Red Hat rating Critical
    RHOAI 3.4.6 - Red Hat OpenShift AI
    • Red Hat OpenShift AI 3.4 registry.redhat.io/rhoai/odh-built-in-detector-rhel9, registry.redhat.io/rhoai/odh-cli-rhel9, registry.redhat.io/rhoai/odh-dashboard-rhel9 +47

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Ansible Automation Orchestrator 2026AffectedNo fix yet
Exploit IntelligenceAffectedNo fix yet
Lightspeed CoreAffectedNo fix yet
Migration Toolkit for Applications 8AffectedNo fix yet
OpenShift LightspeedAffectedNo fix yet
Red Hat AI Inference ServerAffectedNo fix planned: Will not fix
Red Hat Ansible Automation Platform 2AffectedNo fix yet
Red Hat Enterprise Linux AI (RHEL AI) 3AffectedNo fix yet
Red Hat Enterprise Linux command line assistantAffectedNo fix yet
Red Hat OpenShift AI (RHOAI)AffectedNo fix yet
Red Hat OpenShift Virtualization 4AffectedNo fix yet
Red Hat AI Inference Server 3.5Fixed RHSA-2026:94702, RHSA-2026:94709, RHSA-2026:94717, RHSA-2026:94721, RHSA-2026:94738
Red Hat OpenShift AI 3.4Fixed RHSA-2026:92510
Red Hat Satellite 6.18Fixed RHSA-2026:92667
Red Hat Satellite 6.19Fixed RHSA-2026:92666
Not affected: 3 products
  • Red Hat AI Inference Server
  • Red Hat OpenShift AI (RHOAI)
  • Red Hat OpenShift AI 3.4

Timeline

  1. 2026-10-15 Threatist record created from CVE-2026-59951
  2. 2026-10-16 Alias added: GHSA-84m7-p3x7-pcfv
  3. 2026-10-16 Fix available: PyPI/[email protected], PyPI/[email protected] · GHSA-84m7-p3x7-pcfv
  4. 2026-10-16 CVSS score added · GHSA-84m7-p3x7-pcfv
  5. 2026-10-16 Weakness changed · GHSA-84m7-p3x7-pcfv
  6. 2026-10-16 9 new references · GHSA-84m7-p3x7-pcfv
  7. 2026-10-16 CISA SSVC decision points changed
  8. 2026-10-16 Priority changed: MEDIUM → LOW
  9. 2026-10-16 Affected versions changed · Red Hat
  10. 2026-10-16 CVSS score added · Red Hat
  11. 2026-10-21 Affected versions changed · Red Hat
  12. 2026-10-30 Fix available: RHSA-2026:92510 · Red Hat
  13. 2026-10-30 Fix available: Red Hat OpenShift AI 3.4 · Red Hat
  14. 2026-10-30 Fix available: Red Hat Satellite 6.18, Red Hat Satellite 6.19 · Red Hat
  15. 2026-10-31 Fix available: RHSA-2026:92666 · Red Hat
  16. 2026-10-31 Fix available: RHSA-2026:92667 · Red Hat
  17. 2026-11-04 Fix available: RHSA-2026:94717 · Red Hat
  18. 2026-11-04 Fix available: RHSA-2026:94709 · Red Hat
  19. 2026-11-04 Fix available: RHSA-2026:94738 · Red Hat
  20. 2026-11-04 Fix available: RHSA-2026:94702 · Red Hat
  21. 2026-11-04 Fix available: RHSA-2026:94721 · Red Hat
  22. 2026-11-04 Fix available: Red Hat AI Inference Server 3.5 · Red Hat

References

Advisory 1

Other 8

  • TI-2026-46366 Server-side request forgery in mlflow KEVCVSS 3.1CRITICAL 9.3
  • TI-2023-03518 Absolute Path Traversal in mlflow/mlflow CVSS 3.1CRITICAL 10.0
  • TI-2023-01113 Path Traversal: '\..\filename' in mlflow/mlflow CVSS 3.1CRITICAL 9.8
  • TI-2025-31759 Redis Lua Use-After-Free may lead to remote code execution CVSS 3.1CRITICAL 10.0
  • TI-2026-81527 Code execution via scorer deserialization in MLflow servers CVSS 3.1CRITICAL 9.8
  • TI-2025-14028 Command Injection in mlflow/mlflow CVSS 3.1CRITICAL 10.0
See all 175 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences