CVE-2025-64340

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.8 under NVD CVSS v3. EPSS exploit probability: 0.7%, top 49% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this weekElevated
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.8Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
51(Track*)
EG Risk 51/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity78% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
1%
EPSS %ILE
51%
KEV
Not listed

Published

April 3, 2026

Last Modified

July 24, 2026

Advisory Details (2)

Auto-updated Jul 24, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_pr.
github Patch Available🟡 PoC Available

Command injection via server name in subprocess-backed install commands · Advisory · PrefectHQ/fastmcp · GitHub

https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g
github_pr Patch Available

fix: validate server names in install commands

Patch available: PrefectHQ/fastmcp v3.2.0 (PR #3522 merged 2026-03-15)

https://github.com/PrefectHQ/fastmcp/pull/3522

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
fastmcp0.1.0 ... 3.1.1 (91 versions)3.2.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 49× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 116 total refreshes for this CVE.

  1. 2026-07-27 14:12 UTCEPSS rescore
  2. 2026-07-26 14:54 UTCEPSS rescore
  3. 2026-07-26 14:54 UTCEPSS rescore
  4. 2026-07-26 09:19 UTCEG score recompute▲ 1.10
  5. 2026-07-25 14:17 UTCEPSS rescore
  6. 2026-07-24 22:12 UTCNVD updateCVSS v3 → 7.8 · severity → HIGH
  7. 2026-07-24 14:17 UTCEPSS rescore
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  11. 2026-07-23 03:01 UTCEG score recompute
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  20. 2026-07-17 03:54 UTCOSV refresh
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  1. 2026-07-13 22:29 UTCEPSS rescore
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  25. 2026-06-27 03:08 UTCEPSS rescore
  26. 2026-06-25 13:49 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2025-64340?
CVE-2025-64340 is a high vulnerability published on April 3, 2026. 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()…
When was CVE-2025-64340 disclosed?
CVE-2025-64340 was first published in the National Vulnerability Database on April 3, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-64340 actively exploited?
CVE-2025-64340 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 49.3% of all scored CVEs.
What is the CVSS score of CVE-2025-64340?
CVE-2025-64340 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2025-64340?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-64340, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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