{"answers":{"affected":"3 open source packages ship an affected version, including fastmcp. It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-32871 exists.","fix":"Upgrade fastmcp to 3.2.0 or later.","what":"CVE-2026-32871 is a critical server-side request forgery vulnerability in PrefectHQ fastmcp, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-32871 and fix it if it is affected.\n\nWhat it is: CVE-2026-32871 is a critical server-side request forgery vulnerability in PrefectHQ fastmcp, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-32871 exists.\n\nAffected packages and fixed versions:\n- fastmcp (PyPI): affected all versions; fixed in 3.2.0\n- fastmcp (PyPI): affected all versions; fixed in 3.2.0\n- fastmcp (PyPI): affected all versions; fixed in 3.2.0\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-2026-32871/ (Markdown: https://insights.sbomify.com/CVE-2026-32871/index.md)","id":"CVE-2026-32871","markdown":"https://insights.sbomify.com/CVE-2026-32871/index.md","name":"CVE-2026-32871","record":{"aliases":["CLSA-2026-1788514996","ECHO-bd91-e96b-0efc","GHSA-vv7q-7jx5-f767","PYSEC-2026-338","ROOT-APP-PYPI-CVE-2026-32871"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["data_read","security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"Python MCP library","requires_auth":"none","summary":"Attackers can exploit path traversal in URL construction to perform Server-Side Request Forgery and access internal backend APIs.","user_interaction":"not_required","vuln_class":"ssrf"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"fastmcp","vendor":"jlowin"}],"cvss":{"score":10,"severity":"critical","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H","version":"4.0"},"cwes":[{"id":"CWE-918","name":"Server-Side Request Forgery"}],"description":"FastMCP is a Pythonic way to build MCP servers and clients. Prior to version 3.2.0, the OpenAPIProvider in FastMCP exposes internal APIs to MCP clients by parsing OpenAPI specifications. The RequestDirector class is responsible for constructing HTTP requests to the backend service. A vulnerability exists in the _build_url() method. When an OpenAPI operation defines path parameters (e.g., /api/v1/users/{user_id}), the system directly substitutes parameter values into the URL template string without URL-encoding. Subsequently, urllib.parse.urljoin() resolves the final URL. Since urljoin() interprets ../ sequences as directory traversal, an attacker controlling a path parameter can perform path traversal attacks to escape the intended API prefix and access arbitrary backend endpoints. This results in authenticated SSRF, as requests are sent with the authorization headers configured in the MCP provider. This issue has been patched in version 3.2.0.","ecosystems":["PyPI"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"FastMCP OpenAPI Provider has an SSRF \u0026 Path Traversal Vulnerability","id":"CVE-2026-32871","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"PyPI","product":null,"products":[],"type":"ssrf","year":"2026"},"n_packages":3,"n_references":4,"next":{"headline":"ewe: Loop with Unreachable Exit Condition ('Infinite Loop')","id":"CVE-2026-32873"},"packages":[{"ecosystem":"PyPI","fixed":["3.2.0"],"introduced":["0"],"last_affected":[],"package":"fastmcp","purl":null,"source":"GHSA-vv7q-7jx5-f767"},{"ecosystem":"PyPI","fixed":["3.2.0"],"introduced":["0"],"last_affected":[],"package":"fastmcp","purl":"pkg:pypi/fastmcp","source":"GHSA-vv7q-7jx5-f767"},{"ecosystem":"PyPI","fixed":["3.2.0"],"introduced":["0"],"last_affected":[],"package":"fastmcp","purl":"pkg:pypi/fastmcp","source":"PYSEC-2026-338"}],"prev":{"headline":"Kirby has XML injection in its XML creator toolkit","id":"CVE-2026-32870"},"products":["fastmcp"],"published":"2026-04-02","related":[{"cvss_score":8.2,"headline":"FastMCP: Missing Consent Verification in OAuth Proxy Callback Facilitates Confused Deputy Vulnerabilities","id":"CVE-2026-27124","kev_date_added":null,"published":"2026-04-03"},{"cvss_score":7.4,"headline":"FastMCP OAuth Proxy token reuse across MCP servers","id":"CVE-2025-69196","kev_date_added":null,"published":"2026-03-16"},{"cvss_score":6.7,"headline":"FastMCP has a Command Injection vulnerability - Gemini CLI","id":"CVE-2025-64340","kev_date_added":null,"published":"2026-04-03"},{"cvss_score":5.4,"headline":"FastMCP vulnerable to windows command injection in FastMCP Cursor installer via server_name","id":"CVE-2025-62801","kev_date_added":null,"published":"2025-10-28"},{"cvss_score":5.3,"headline":"FastMCP vulnerable to reflected XSS in client's callback page","id":"CVE-2025-62800","kev_date_added":null,"published":"2025-10-28"}],"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":"yes","exploitation":"poc","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-07-15","vendors":["PrefectHQ"]},"summary":"Attackers can exploit path traversal in URL construction to perform Server-Side Request Forgery and access internal backend APIs.","url":"https://insights.sbomify.com/CVE-2026-32871/"}