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TI-2026-74371 Aliases CVE-2026-109527

Memory exhaustion in MCP Python SDK via unbounded request bodies

Priority MEDIUM 40CWE-770Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 3 fixed, 11 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-770.

Summary

The Model Context Protocol Python SDK (mcp) versions before 1.29.1 and from 2.0.0a1 through 2.0.1 are affected. The Streamable HTTP session manager, SSE message endpoint and OAuth authorization-server routes buffer complete HTTP request bodies without a maximum size (CWE-770). An unauthenticated remote client that can reach an affected endpoint can send a large request body that consumes many times its size in process memory, repeatedly exhausting memory or terminating the server.

Written with Claude Haiku 5.5 from the sources below · 2026-10-31

Description from the CNA

The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. In mcp versions before 1.29.1 and from 2.0.0a1 through 2.0.1, the Streamable HTTP session manager, SSE message endpoint, and OAuth authorization-server routes buffer complete HTTP request bodies without enforcing a maximum size. An unauthenticated remote client able to reach an affected endpoint can send a large declared or streamed request body that consumes multiple times the body size in process memory and can repeatedly exhaust memory or terminate the server. Stdio-only servers and deployments with an effective upstream request-size limit are not affected, and applications that use StreamableHTTPServerTransport directly remain responsible for enforcing their own limit. The standard SDK server applications and session managers are fixed in versions 1.29.1 and 2.1.0.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.007 53rd percentileScored 2026-11-07
Fix Partial python-sdk (modelcontextprotocol): 1.29.1, 2.1.0Red Hat: 3 advisoriesRed Hat: 3 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-sdkbefore 1.29.1; 2.0.0a1 to before 2.1.01.29.1, 2.1.0Patch availableCNA
  • python-sdk VendorMLflow Affected before 1.29.1; 2.0.0a1 to before 2.1.0 Fixed in 1.29.1, 2.1.0 Patch available CNA

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 modelcontextprotocol python-sdk package to version 1.29.1 or 2.1.0. Red Hat fixes this in RHSA-2026:92667 (Red Hat Satellite 6.18), RHSA-2026:92666 (Red Hat Satellite 6.19) and RHSA-2026:92510 (Red Hat OpenShift AI 3.4). The sources list no fixed version for Ansible Automation Orchestrator 2026, Exploit Intelligence, Lightspeed Core, Migration Toolkit for Applications 8, OpenShift Lightspeed and other Red Hat products.

Written with Claude Haiku 5.5 from the sources below · 2026-10-31

  • Fix · CNA python-sdk (modelcontextprotocol) Fixed in 1.29.1, 2.1.0

Red Hat 3 advisories

  • 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 yet
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 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-2026-109527
  2. 2026-10-16 Priority changed: MEDIUM → LOW
  3. 2026-10-16 Affected versions changed · Red Hat
  4. 2026-10-16 CVSS score added · Red Hat
  5. 2026-10-20 CISA SSVC decision points changed
  6. 2026-10-20 Priority changed: LOW → MEDIUM
  7. 2026-10-21 Affected versions changed · Red Hat
  8. 2026-10-30 Fix available: RHSA-2026:92510 · Red Hat
  9. 2026-10-30 Fix available: Red Hat OpenShift AI 3.4 · Red Hat
  10. 2026-10-30 Fix available: Red Hat Satellite 6.18, Red Hat Satellite 6.19 · Red Hat
  11. 2026-10-31 Fix available: RHSA-2026:92666 · Red Hat
  12. 2026-10-31 Fix available: RHSA-2026:92667 · Red Hat

References

Other 7

  • 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