CVE-2026-5327: Fast filesystem mcp Fast-filesystem-mcp Is Vulnerable To Command Vulnerability

LOW
Advisory Identifier: GHSA-5226-3rvg-hp4x
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CVSS 6.3
CWE-74
Published
Advisory Summary

CVE-2026-5327 is a LOW (CVSS 6.3) fast-filesystem-mcp is vulnerable to command vulnerability (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')) affecting Fast filesystem mcp libraries in the npm ecosystem. The issue involves fast-filesystem-mcp is vulnerable to command injection through handlegetdiskusage function. Remediation is available in the latest vendor maintenance releases.

CVE-2026-5327 at a Glance

CVE Identifier CVE-2026-5327
GHSA Identifier GHSA-5226-3rvg-hp4x
Severity LOW
CVSS v3.1 Base Score 6.3
CWE Classification CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Affected Product Fast filesystem mcp
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 6.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2026-5327

To remediate this vulnerability, upgrade all affected Fast filesystem mcp dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

fast-filesystem-mcp fixed: Latest secure release 
npm install fast-filesystem-mcp@Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls fast-filesystem-mcp

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-5327, inspect your project dependencies using npm:

npm ls fast-filesystem-mcp

Analyze the terminal output to locate any version of Fast filesystem mcp in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The npm ls fast-filesystem-mcp command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection'), where the product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. In Fast filesystem mcp, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-5327 Affected Fast filesystem mcp Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
fast-filesystem-mcp
npm/fast-filesystem-mcp
npm
≤ 3.5.0

References

NVD — CVE-2026-5327 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-5327
Fast filesystem mcp Source Repository REPOSITORY
https://github.com/efforthye/fast-filesystem-mcp/issues/15
Fast filesystem mcp Source Repository REPOSITORY
https://github.com/efforthye/fast-filesystem-mcp
Fast filesystem mcp Source Repository REPOSITORY
https://github.com/user-attachments/files/25822878/fast-filesystem-mcp_bug.pdf
vuldb.com/submit/780776 WEB
https://vuldb.com/submit/780776
vuldb.com/vuln/354658 WEB
https://vuldb.com/vuln/354658
vuldb.com/vuln/354658/cti WEB
https://vuldb.com/vuln/354658/cti

Frequently Asked Questions

What is CVE-2026-5327?
CVE-2026-5327 is a security vulnerability in Fast filesystem mcp involving fast-filesystem-mcp is vulnerable to command injection through handleGetDiskUsage function under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection').
Which Fast filesystem mcp versions are affected?
Affected versions include releases prior to current release patches across affected packages: fast-filesystem-mcp.
What version fixes CVE-2026-5327?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is fast-filesystem-mcp affected?
Yes, fast-filesystem-mcp is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2026-5327?
CVE-2026-5327 has a CVSS v3.1 base score of 6.3 (LOW) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L.
What CWE is associated with CVE-2026-5327?
CVE-2026-5327 is classified under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.).
How can I check npm dependencies for CVE-2026-5327?
Run the dependency tree command: 'npm ls fast-filesystem-mcp'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-5226-3rvg-hp4x",
  "modified" : "2026-04-04T05:39:06Z",
  "published" : "2026-04-02T12:31:05Z",
  "aliases" : [ "CVE-2026-5327" ],
  "summary" : "fast-filesystem-mcp is vulnerable to command injection through handleGetDiskUsage function",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "fast-filesystem-mcp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "3.5.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-5327"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/efforthye/fast-filesystem-mcp/issues/15"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/efforthye/fast-filesystem-mcp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/user-attachments/files/25822878/fast-filesystem-mcp_bug.pdf"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/submit/780776"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/vuln/354658"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/vuln/354658/cti"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-74" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-04T05:39:06Z",
    "nvd_published_at" : "2026-04-02T12:16:21Z"
  }
}