---
id: "CVE-2026-118384"
kind: "vulnerability"
aliases: ["CVE-2026-118384"]
title: "GNU mtools: out-of-bounds write in FAT parsing may corrupt memory"
severity: "medium"
cvss: 6.1
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["disk-images", "embedded", "linux", "mtools", "other"]
not_affected_if: ["no-untrusted-fat-images"]
published_at: "2026-10-28T03:17:14+00:00"
first_seen_at: "2026-10-28T03:31:02+00:00"
updated_at: "2026-10-28T03:32:45+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-118384", "first_seen_at": "2026-10-28T03:31:02+00:00"}]
---

# GNU mtools: out-of-bounds write in FAT parsing may corrupt memory

GNU mtools through 4.0.49 has an out-of-bounds write in the parse_vses function in vfat.c, which handles VFAT long file names. A crafted FAT disk image processed by mtools can write memory outside its buffer, which can crash the tool or possibly run attacker-controlled code.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `mtools --version` (or `mtools -V`) to see whether the installed version is 4.0.49 or earlier.
- Run `dpkg -l mtools` or `rpm -q mtools` to confirm the packaged version on Linux.

## Fix

- Upgrade mtools to a release later than `4.0.49` once a fixed version is published by your distribution; the sources do not name a fixed version.
- Until patched, avoid running mtools on untrusted disk images.

## Timeline

- 2026-10-28T03:31:02+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-118384

## From the sources

GNU mtools through 4.0.49 has an out-of-bounds write in parse_vses in vfat.c.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_