CVE-2025-64340 json
FastMCP has a Command Injection vulnerability - Gemini CLI
published 2026-03-31 7 mo ago modified 2026-09-10 1 mo ago also EUVD-2025-209207 , GHSA-m8x7-r2rg-vh5g , PYSEC-2026-2475
- cvss
- 6.7
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 55%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- pypi fastmcp 3.2.0
- jlowin fastmcp 3.2.0
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- total
- Assessed
- 7 mo ago
Exploit prediction
0.75% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.7 | CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 6.7 | CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H |
| NVD | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| OSV | 3.1 | 6.7 | CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | fastmcp | <3.2.0 |
3.2.0 |
Affected products
- jlowin fastmcp
Classification
- Weakness
-
- CWE-78 Improper Neutralization of Special Elements used in an OS Command
References
-
github.com
/PrefectHQ/fastmcp/pull/3522
web, issue-tracking, patch
-
github.com
/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g
exploit, web, patch, vendor-advisory
-
github.com
/jlowin/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g
web
-
nvd.nist.gov
/vuln/detail/CVE-2025-64340
advisory
-
github.com
/PrefectHQ/fastmcp
package
-
pypi.org
/project/fastmcp
package
-
github.com
/advisories/GHSA-m8x7-r2rg-vh5g
advisory
Sources
- CVE List CVE-2025-64340
- GitHub Advisory GHSA-m8x7-r2rg-vh5g
- NVD CVE-2025-64340
- OSV PYSEC-2026-2475
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.