{"answers":{"affected":"3 open source packages ship an affected version, including mcp. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-52869 in the wild and no public exploit code.","fix":"Upgrade mcp to 1.27.2 or later.","what":"CVE-2026-52869 is a high-severity missing authorization vulnerability in modelcontextprotocol python-sdk, published on 15 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-52869 and fix it if it is affected.\n\nWhat it is: CVE-2026-52869 is a high-severity missing authorization vulnerability in modelcontextprotocol python-sdk, published on 15 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-52869 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- mcp (PyPI): affected all versions; fixed in 1.27.2\n- mcp (PyPI): affected all versions; fixed in 1.27.2\n- mcp (PyPI): affected all versions; fixed in 1.27.2\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-52869/ (Markdown: https://insights.sbomify.com/CVE-2026-52869/index.md)","id":"CVE-2026-52869","markdown":"https://insights.sbomify.com/CVE-2026-52869/index.md","name":"CVE-2026-52869","record":{"aliases":["ECHO-5da5-33db-f402","GHSA-jpw9-pfvf-9f58","MINI-24xq-v9j2-hcfp","MINI-3225-g9hp-39wm","MINI-34ph-9368-jwf6","MINI-53f5-8x3p-x6w4","MINI-7542-wp76-8r9f","MINI-87q4-r73x-fmqr","MINI-crwp-vp3w-pxfw","MINI-f853-6gp2-pvww","MINI-g4pj-f8mc-jvv6","MINI-gcwr-pqq5-p5xp","MINI-hjm6-823x-5xc6","MINI-j2mq-j8jv-586h","MINI-rwmf-jqhq-3j5f","MINI-vqv5-h76g-g34h","MINI-wpgw-9pv6-wf5v","MINI-xp8p-78px-gg6x","PYSEC-2026-3482","ROOT-APP-PYPI-CVE-2026-52869"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["data_modify","security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"MCP Python SDK","requires_auth":"low_privilege","summary":"Attackers can inject JSON-RPC messages into existing sessions by guessing session IDs, bypassing authentication checks in the MCP Python SDK.","user_interaction":"not_required","vuln_class":"missing_authorization"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"mcp_python_sdk","vendor":"lfprojects"}],"cvss":{"score":7.1,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L","version":"3.1"},"cwes":[{"id":"CWE-639","name":"Authorization Bypass Through User-Controlled Key"}],"description":"The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to 1.27.2, the SSE and stateful Streamable HTTP transports mcp.server.sse.SseServerTransport and mcp.server.streamable_http_manager.StreamableHTTPSessionManager route requests to existing sessions using only the session_id query parameter or Mcp-Session-Id header without verifying the authenticated principal that created the session, allowing a different bearer-token-authenticated client with a known session ID to inject JSON-RPC messages into that session. This issue is fixed in version 1.27.2.","ecosystems":["PyPI"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"MCP Python SDK: HTTP transports serve session requests without verifying the authenticated principal","id":"CVE-2026-52869","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"PyPI","product":null,"products":[],"type":"missing_authorization","year":"2026"},"n_packages":3,"n_references":6,"next":{"headline":"MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks","id":"CVE-2026-52870"},"packages":[{"ecosystem":"PyPI","fixed":["1.27.2"],"introduced":["0"],"last_affected":[],"package":"mcp","purl":null,"source":"GHSA-jpw9-pfvf-9f58"},{"ecosystem":"PyPI","fixed":["1.27.2"],"introduced":["0"],"last_affected":[],"package":"mcp","purl":"pkg:pypi/mcp","source":"GHSA-jpw9-pfvf-9f58"},{"ecosystem":"PyPI","fixed":["1.27.2"],"introduced":["0"],"last_affected":[],"package":"mcp","purl":"pkg:pypi/mcp","source":"PYSEC-2026-3482"}],"prev":{"headline":"OFFIS DCMTK Toolkit Path Traversal","id":"CVE-2026-52868"},"products":["python-sdk"],"published":"2026-07-15","related":[{"cvss_score":7.6,"headline":"MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks","id":"CVE-2026-52870","kev_date_added":null,"published":"2026-07-15"},{"cvss_score":7.6,"headline":"MCP Python SDK: WebSocket server transport does not support Host/Origin validation","id":"CVE-2026-59950","kev_date_added":null,"published":"2026-07-15"},{"cvss_score":7.6,"headline":"DNS Rebinding Protection Disabled by Default in Model Context Protocol Python SDK for Servers Running on Localhost","id":"CVE-2025-66416","kev_date_added":null,"published":"2025-12-02"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CC BY 4.0","name":"PyPA Advisory Database","prefix":"PYSEC"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-07-16","vendors":["modelcontextprotocol"]},"summary":"Attackers can inject JSON-RPC messages into existing sessions by guessing session IDs, bypassing authentication checks in the MCP Python SDK.","url":"https://insights.sbomify.com/CVE-2026-52869/"}