{ "document": { "category": "csaf_base", "csaf_version": "2.0", "distribution": { "tlp": { "label": "WHITE" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings." } ], "publisher": { "category": "coordinator", "contact_details": "cert@ncsc.nl", "name": "National Cyber Security Centre", "namespace": "https://www.ncsc.nl/" }, "title": "CVE-2025-64340", "tracking": { "current_release_date": "2026-04-03T16:46:51.945427Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2025-64340", "initial_release_date": "2026-03-31T23:07:46.582595Z", "revision_history": [ { "date": "2026-03-31T23:07:46.582595Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (4).| CWES updated (1)." }, { "date": "2026-03-31T23:07:54.662172Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-04-03T15:41:06.184305Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| References created (2).| CWES updated (1)." }, { "date": "2026-04-03T15:41:08.175367Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-04-03T16:39:23.108235Z", "number": "5", "summary": "Unknown change." }, { "date": "2026-04-03T16:46:41.571018Z", "number": "6", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-04-03T16:46:49.409859Z", "number": "7", "summary": "NCSC Score updated." } ], "status": "interim", "version": "7" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<3.2.0", "product": { "name": "vers:unknown/<3.2.0", "product_id": "CSAFPID-5992235" } } ], "category": "product_name", "name": "fastmcp" } ], "category": "vendor", "name": "jlowin" } ] }, "vulnerabilities": [ { "cve": "CVE-2025-64340", "cwe": { "id": "CWE-78", "name": "Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')" }, "notes": [ { "category": "description", "text": "Server names containing shell metacharacters (e.g., `&`) can cause command injection on Windows when passed to `fastmcp install claude-code` or `fastmcp install gemini-cli`. These install paths use `subprocess.run()` with a list argument, but on Windows the target CLIs often resolve to `.cmd` wrappers that are executed through `cmd.exe`, which interprets metacharacters in the flattened command string.\n\nPoC:\n```python\nfrom fastmcp import FastMCP\n\nmcp = FastMCP(name=\"test&calc\")\n\n@mcp.tool\ndef roll_dice(n_dice: int) -> list[int]:\n \"\"\"Roll `n_dice` 6-sided dice and return the results.\"\"\"\n return [random.randint(1, 6) for _ in range(n_dice)]\n```\n\n```\nfastmcp install claude-code server.py # or: fastmcp install gemini-cli server.py\n```\n\nOn Windows, this opens Calculator via the `&calc` in the server name.\n\nImpact:\nArbitrary command execution with the privileges of the user running `fastmcp install`. Affects Windows hosts where the target CLI (one of claude, gemini) is installed as a `.cmd` wrapper. Does not affect macOS/Linux, and does not affect config-file-based install targets (cursor, goose, mcp-json).\n\nPatched in #3522 by validating server names to reject shell metacharacters.", "title": "github - https://api.github.com/advisories/GHSA-m8x7-r2rg-vh5g" }, { "category": "description", "text": "FastMCP is the standard framework for building MCP applications. Prior to version 3.2.0, server names containing shell metacharacters (e.g., &) can cause command injection on Windows when passed to fastmcp install claude-code or fastmcp install gemini-cli. These install paths use subprocess.run() with a list argument, but on Windows the target CLIs often resolve to .cmd wrappers that are executed through cmd.exe, which interprets metacharacters in the flattened command string. This issue has been patched in version 3.2.0.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2025/64xxx/CVE-2025-64340.json" }, { "category": "description", "text": "FastMCP is the standard framework for building MCP applications. Prior to version 3.2.0, server names containing shell metacharacters (e.g., &) can cause command injection on Windows when passed to fastmcp install claude-code or fastmcp install gemini-cli. These install paths use subprocess.run() with a list argument, but on Windows the target CLIs often resolve to .cmd wrappers that are executed through cmd.exe, which interprets metacharacters in the flattened command string. This issue has been patched in version 3.2.0.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2025-64340" }, { "category": "other", "text": "3.9", "title": "NCSC Score" }, { "category": "other", "text": "There is cwe data available from source Nvd", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5992235" ] }, "references": [ { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-m8x7-r2rg-vh5g" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2025/64xxx/CVE-2025-64340.json" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2025-64340" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/jlowin/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/PrefectHQ/fastmcp/pull/3522" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-m8x7-r2rg-vh5g" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H", "baseScore": 6.7, "baseSeverity": "MEDIUM" }, "products": [ "CSAFPID-5992235" ] } ], "title": "CVE-2025-64340" } ] }