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

> Remote attackers can execute arbitrary commands via the handleGetDiskUsage function in the fast-filesystem-mcp library.

- **Severity:** Medium 5.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 2 Apr 2026
- **Updated:** 2 Apr 2026
- **Also known as:** GHSA-5226-3rvg-hp4x

## What is CVE-2026-5327?

CVE-2026-5327 is a medium-severity command injection vulnerability in efforthye fast-filesystem-mcp, published on 2 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.

Weakness: CWE-77 (Improper Neutralization of Special Elements used in a Command), CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2026-5327?

2 open source packages ship an affected version, including fast-filesystem-mcp.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `fast-filesystem-mcp` | npm | All versions to 3.5.0 | None |
| `fast-filesystem-mcp` | npm | All versions to 3.5.0 | None |

## How do I fix CVE-2026-5327?

No fix has been published for CVE-2026-5327 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5327 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5327 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5327 and fix it if it is affected.

What it is: CVE-2026-5327 is a medium-severity command injection vulnerability in efforthye fast-filesystem-mcp, published on 2 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5327 exists.

Affected packages and fixed versions:
- fast-filesystem-mcp (npm): affected all versions up to 3.5.0; no fix listed
- fast-filesystem-mcp (npm): affected all versions up to 3.5.0; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-5327/ (Markdown: https://insights.sbomify.com/CVE-2026-5327/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5327
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5327
- OSV: https://osv.dev/vulnerability/CVE-2026-5327

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5327/
Summaries are generated and may contain mistakes; the official description above is the record.