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CVE-2026-59951

MEDIUM 6.9

Published 2026-10-14 · Last modified 2026-10-15

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.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.5%chance of exploitation in 30 days · 39th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

6.9CVSS 4.0 · MEDIUM

  • ConfidentialityNone
  • IntegrityNone
  • AvailabilityLow

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable
  • ✓Requirements: No special attack requirements

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

Search GitHub now — results may be empty or unverified.

Tracked sources are checked daily for recent CVEs, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Data snapshot:

Affected

Vendors Modelcontextprotocol

Products Python Sdk

Weakness (CWE)

  • CWE-400: : Uncontrolled Resource Consumption
  • CWE-772: : Missing Release of Resource after Effective Lifetime

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

References and research data (JSON)

Packages and version ranges

Each advisory describes its own package and affected ranges. A boundary applies to that range; it is not a universal upgrade recommendation.

  • mcp PyPI

    pkg:pypi/mcp

    ECOSYSTEM range
    • Introduced version (included): 1.8.0
    • Fixed boundary (excluded): 1.30.0
    43 explicitly listed affected versions

    1.10.0, 1.10.1, 1.11.0, 1.12.0, 1.12.1, 1.12.2, 1.12.3, 1.12.4, 1.13.0, 1.13.1, 1.14.0, 1.14.1, 1.15.0, 1.16.0, 1.17.0, 1.18.0, 1.19.0, 1.20.0, 1.21.0, 1.21.1, 1.21.2, 1.22.0, 1.23.0, 1.23.1, 1.23.2, 1.23.3, 1.24.0, 1.25.0, 1.26.0, 1.27.0, 1.27.1, 1.27.2, 1.28.0, 1.28.1, 1.29.0, 1.29.1, 1.8.0, 1.8.1, 1.9.0, 1.9.1, 1.9.2, 1.9.3, 1.9.4

    Additional upstream package constraints
    {
  "database": {
    "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-84m7-p3x7-pcfv/GHSA-84m7-p3x7-pcfv.json"
  }
}
    GitHub Advisory Database · GHSA-84m7-p3x7-pcfv · Updated 2026-10-15T20:30:08.565001293Z
  • mcp PyPI

    pkg:pypi/mcp

    ECOSYSTEM range
    • Introduced version (included): 2.0.0
    • Fixed boundary (excluded): 2.2.0
    4 explicitly listed affected versions

    2.0.0, 2.0.1, 2.1.0, 2.1.1

    Additional upstream package constraints
    {
  "database": {
    "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-84m7-p3x7-pcfv/GHSA-84m7-p3x7-pcfv.json"
  }
}
    GitHub Advisory Database · GHSA-84m7-p3x7-pcfv · Updated 2026-10-15T20:30:08.565001293Z

Vendor product assessments

Showing 32 of 46 vendor product statements; 14 omitted. Read the full vendor advisory.

  • ansible-automation-platform/automation-orchestrator-backend-rhel9 as a component of Ansible Automation Orchestrator 2026 · known affected

    Vendor assessment for this product only.

    pkg:oci/automation-orchestrator-backend-rhel9@sha256:93abb3e4ab9571eb09b2de296321d12fdb38d2fa3c32c13cd304ab0db062e591?repository_url=registry.redhat.io/ansible-automation-platform/automation-orchestrator-backend-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • lightspeed-core/lightspeed-stack-rhel9 as a component of Lightspeed Core · known affected

    Vendor assessment for this product only.

    pkg:oci/lightspeed-stack-rhel9@sha256:c8b39c58ade51ce26698f5d3c8d302e2e039f05ff14e014b17da2cba0f8c8068?repository_url=registry.redhat.io/lightspeed-core/lightspeed-stack-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • lightspeed-core/rag-tool-cpu-rhel9 as a component of Lightspeed Core · known affected

    Vendor assessment for this product only.

    pkg:oci/rag-tool-cpu-rhel9@sha256:ec8e42910dd3a7109d90bf77bb47e198a1580875117dc4b5365b5a85d2d8325c?repository_url=registry.redhat.io/lightspeed-core/rag-tool-cpu-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • mta/mta-solution-server-rhel9 as a component of Migration Toolkit for Applications 8 · known affected

    Vendor assessment for this product only.

    pkg:oci/mta-solution-server-rhel9@sha256:ee4dbe222bd778ef272ddf3e59dac0844289cc719cd87dea1e24df74f344e097?repository_url=registry.redhat.io/mta/mta-solution-server-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • openshift-lightspeed/lightspeed-agentic-sandbox-rhel9 as a component of OpenShift Lightspeed · known affected

    Vendor assessment for this product only.

    pkg:oci/lightspeed-agentic-sandbox-rhel9@sha256:d40dff970b3c17d3e0edb23b09da9ae08bac9d3eb81887eae358e041e1923b54?repository_url=registry.redhat.io/openshift-lightspeed/lightspeed-agentic-sandbox-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhaii/vllm-cpu-rhel9 as a component of Red Hat AI Inference Server · known affected

    Vendor assessment for this product only.

    pkg:oci/vllm-cpu-rhel9@sha256:81c5994dc20321f8bd3969099eade78ef127cbd79f2d0ccea101c773e4c7fa4d?repository_url=registry.redhat.io/rhaii/vllm-cpu-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhaii/vllm-cuda-rhel9 as a component of Red Hat AI Inference Server · known affected

    Vendor assessment for this product only.

    pkg:oci/vllm-cuda-rhel9@sha256:0d22e2301ce26ef68effda5d3a4a20381ad0ea34d1240e159e245bd44c2e125b?repository_url=registry.redhat.io/rhaii/vllm-cuda-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhaii/vllm-neuron-rhel9 as a component of Red Hat AI Inference Server · known affected

    Vendor assessment for this product only.

    pkg:oci/vllm-neuron-rhel9@sha256:1079c9afecdbc33f4790792f0d712dbf7523790a92dcfbe8fb5cf4c2d282fc5b?repository_url=registry.redhat.io/rhaii/vllm-neuron-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhaii/vllm-rocm-rhel9 as a component of Red Hat AI Inference Server · known affected

    Vendor assessment for this product only.

    pkg:oci/vllm-rocm-rhel9@sha256:1a30359d6ca5d0891e403b9b0a23c0ae1ad6e30a2429b9b42e246b874fe8859a?repository_url=registry.redhat.io/rhaii/vllm-rocm-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhaii/vllm-tpu-rhel9 as a component of Red Hat AI Inference Server · known affected

    Vendor assessment for this product only.

    pkg:oci/vllm-tpu-rhel9@sha256:0c2ac747d67dc0e80162ff05867dd702e474b2217659f19f28b8e3a0c03a942a?repository_url=registry.redhat.io/rhaii/vllm-tpu-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • ansible-automation-platform-26/mcp-tools-rhel9 as a component of Red Hat Ansible Automation Platform 2 · known affected

    Vendor assessment for this product only.

    pkg:oci/mcp-tools-rhel9@sha256:0dcdca84ec4a9430360a262126095e1a06646137d96806bde5cc226733ffbca3?repository_url=registry.redhat.io/ansible-automation-platform-26/mcp-tools-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • ansible-automation-platform-27/lightspeed-chatbot-rhel9 as a component of Red Hat Ansible Automation Platform 2 · known affected

    Vendor assessment for this product only.

    pkg:oci/lightspeed-chatbot-rhel9@sha256:90ab0d048385b72c760d57c2eb194dfbc0224176e3bd8fc0dccb31eebf6fe8c5?repository_url=registry.redhat.io/ansible-automation-platform-27/lightspeed-chatbot-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhelai3/bootc-aws-cuda-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3 · known affected

    Vendor assessment for this product only.

    pkg:oci/bootc-aws-cuda-rhel9@sha256:06b1e9b7df858121b6f339a5e78de93307be96c191a1c3e6df50cfeffaf9df15?repository_url=registry.redhat.io/rhelai3/bootc-aws-cuda-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhelai3/bootc-azure-cuda-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3 · known affected

    Vendor assessment for this product only.

    pkg:oci/bootc-azure-cuda-rhel9@sha256:698d9e34aaf479d0149ea75b841dacbe0117ba2e3718a7088ac98ea6b081792e?repository_url=registry.redhat.io/rhelai3/bootc-azure-cuda-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhelai3/bootc-cuda-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3 · known affected

    Vendor assessment for this product only.

    pkg:oci/bootc-cuda-rhel9@sha256:e0fbb896811ab54d183e23612030072b946674824bad697bf2b3f68362651662?repository_url=registry.redhat.io/rhelai3/bootc-cuda-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhelai3/bootc-gaudi-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3 · known affected

    Vendor assessment for this product only.

    pkg:oci/bootc-gaudi-rhel9@sha256:e1057b59ca1be9501332abf97230855e85c7df858356be0da9dce230ea7e98e1?repository_url=registry.redhat.io/rhelai3/bootc-gaudi-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhelai3/bootc-rocm-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3 · known affected

    Vendor assessment for this product only.

    pkg:oci/bootc-rocm-rhel9@sha256:8fe5203e86917e5f829bd64b831cad31536d23a213b4bfe31e652577ad0faf2e?repository_url=registry.redhat.io/rhelai3/bootc-rocm-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhai-early-access/docling-serve-cuda-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known affected

    Vendor assessment for this product only.

    pkg:oci/docling-serve-cuda-rhel9@sha256:d4393882dd9adc9ee6fd03265bb20d90944906a4fa6b37db5b0a47df36ebac75?repository_url=registry.redhat.io/rhai-early-access/docling-serve-cuda-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhoai/odh-feature-server-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known affected

    Vendor assessment for this product only.

    pkg:oci/odh-feature-server-rhel9@sha256:c5dd868cd66e7911969f60658d31b3714ed42f0e81b9512f89991a412bcb0fa9?repository_url=registry.redhat.io/rhoai/odh-feature-server-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhoai/odh-kserve-controller-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known affected

    Vendor assessment for this product only.

    pkg:oci/odh-kserve-controller-rhel9@sha256:c15f0cdab6447446384bbd911bd48368839d0eb20c02e287236e6c905bf34cba?repository_url=registry.redhat.io/rhoai/odh-kserve-controller-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhoai/odh-kserve-router-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known affected

    Vendor assessment for this product only.

    pkg:oci/odh-kserve-router-rhel9@sha256:0e46fd236b218fb33ffe90592f67b50d2f286356f23ecc2c4ec5ae67fa64b57a?repository_url=registry.redhat.io/rhoai/odh-kserve-router-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhoai/odh-llama-stack-core-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known affected

    Vendor assessment for this product only.

    pkg:oci/odh-llama-stack-core-rhel9@sha256:e60cc260f4d1434443572e4ca096b9c1daccd0f046803d716f0521856e837151?repository_url=registry.redhat.io/rhoai/odh-llama-stack-core-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhoai/odh-llm-d-kv-cache-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known affected

    Vendor assessment for this product only.

    pkg:oci/odh-llm-d-kv-cache-rhel9@sha256:cb5eedeefd2578cd9bd8637250bbe299c84539f57b4ead75d630ed9f833a6ef2?repository_url=registry.redhat.io/rhoai/odh-llm-d-kv-cache-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhoai/odh-th-torch-cuda-py312-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known affected

    Vendor assessment for this product only.

    pkg:oci/odh-th-torch-cuda-py312-rhel9@sha256:efd7b3607b699092c68359d20ef0d0043114191a097637667c0d2cf78fbea702?repository_url=registry.redhat.io/rhoai/odh-th-torch-cuda-py312-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhoai/odh-trustyai-garak-lls-provider-dsp-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known affected

    Vendor assessment for this product only.

    pkg:oci/odh-trustyai-garak-lls-provider-dsp-rhel9@sha256:63d2a0d4195c108c2957445ca81e176b8af8e1246205a0c9d1f56d5884aacd29?repository_url=registry.redhat.io/rhoai/odh-trustyai-garak-lls-provider-dsp-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • satellite/foreman-mcp-server-rhel9 as a component of Red Hat Satellite 6 · known affected

    Vendor assessment for this product only.

    pkg:oci/foreman-mcp-server-rhel9@sha256:a2a11b050f7e0b7ea0ebf07d159eef351b3d8ef44c5d5b166b9975e9e513074f?repository_url=registry.redhat.io/satellite/foreman-mcp-server-rhel9

    • none available: Affected
    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhaiis/vllm-cpu-rhel9 as a component of Red Hat AI Inference Server · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/vllm-cpu-rhel9@sha256:fb7791bbfea99e9f81529fe8cc1e7c834ca470585c27590e3d0a6834167cd436?repository_url=registry.redhat.io/rhaiis/vllm-cpu-rhel9

    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhaiis/vllm-cuda-rhel9 as a component of Red Hat AI Inference Server · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/vllm-cuda-rhel9@sha256:73bbc4560132c4aaa9bbd608ce9560eeae7b30bcc8f014da460afa5622139372?repository_url=registry.redhat.io/rhaiis/vllm-cuda-rhel9

    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhaiis/vllm-rocm-rhel9 as a component of Red Hat AI Inference Server · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/vllm-rocm-rhel9@sha256:37b64a8df90756aae0ee96d2f07765adbce5ed5beb2414ac3845806ad2219cfc?repository_url=registry.redhat.io/rhaiis/vllm-rocm-rhel9

    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhaiis/vllm-tpu-rhel9 as a component of Red Hat AI Inference Server · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/vllm-tpu-rhel9@sha256:b1c12112a1e8a298645e10d34d44c9961a6121aa8d87fc5d65ad83e1ffa3c586?repository_url=registry.redhat.io/rhaiis/vllm-tpu-rhel9

    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhoai/odh-openvino-model-server-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known not affected

    Vendor assessment for this product only.

    Reason: component not present

    pkg:oci/odh-openvino-model-server-rhel9@sha256:725ffc572dcbb3a515b9dbd3336c1c663f025aacc5f0ebe2f3a4836765d45055?repository_url=registry.redhat.io/rhoai/odh-openvino-model-server-rhel9

    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00
  • rhoai/odh-vllm-gaudi-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/odh-vllm-gaudi-rhel9@sha256:87eec3862eb6ddef445f89dcf6fd89add7ef202ea7c563b1ee7347537fb3e250?repository_url=registry.redhat.io/rhoai/odh-vllm-gaudi-rhel9

    Red Hat · CVE-2026-59951 · Updated 2026-10-20T19:53:29+00:00

All CVSS metrics

  • MEDIUM 6.9 v4.0 · CNA Primary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
  • MEDIUM 6.9 v4.0 · NVD Secondary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS