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Debian LinuxOperating system · Debian

CVE-2021-39263

HIGH · 7.8 CVSS v3.1 Published 2021-09-07
Fix available
A fix is available. Upgrade to 2021.8.22 or later.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A crafted NTFS image can trigger a heap-based buffer overflow, caused by an unsanitized attribute in ntfs_get_attribute_value, in NTFS-3G < 2021.8.22.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A heap-based buffer overflow vulnerability exists in NTFS-3G versions prior to 2021.8.22. The ntfs_get_attribute_value function fails to properly sanitize attribute values read from crafted NTFS images, allowing an attacker to trigger overflow via a maliciously crafted filesystem.

MitigationUpgrade NTFS-3G to version 2021.8.22 or later to obtain the patched version with proper attribute value sanitization.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Debian LinuxOperating system
Affected:= 9.0= 10.0= 11.0
Ntfs 3gApplication
Affected:< 2021.8.22

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if NTFS-3G is installed
    Run 'dpkg -l ntfs-3g' on Debian-based systems or 'rpm -qa | grep -i ntfs-3g' on RHEL-based systems. If the package is not installed, this vulnerability does not apply.
    Affected if NTFS-3G package is present on the system
  2. Determine the installed NTFS-3G version
    Run 'ntfs-3g --version' or 'dpkg -l ntfs-3g' to obtain the exact version number.
    Affected if The installed version is earlier than 2021.8.22 (e.g., 2021.1.15, 2020.x.x, or older)
  3. Identify if NTFS-3G is used for automatic mounting
    Check for configured NTFS mounts in /etc/fstab and /media, or review any automount configurations that may mount NTFS filesystems without user intervention.
    Affected if NTFS-3G is configured to automatically mount NTFS partitions (especially external or removable drives) as this increases exposure to untrusted images
  4. Check for tools that parse NTFS images directly
    Review installed forensic or disk utilities that use NTFS-3G libraries to process NTFS images (such as 'ntfsclone', 'ntfsinfo', or similar tools).
    Affected if Tools that can open or parse NTFS image files are in use, as the vulnerability can be triggered by opening a maliciously crafted NTFS image file

You are affected if NTFS-3G is installed and the installed version is earlier than 2021.8.22, especially if the system mounts untrusted NTFS images or uses NTFS-3G-based tools to process external image files.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2021.8.22 or later
Fixed in 2021.8.22
Interim mitigation

Upgrade NTFS-3G to version 2021.8.22 or later to obtain the patched version with proper attribute value sanitization.

Recommended fix High confidence

NTFS-3G version 2021.8.22 or later

  1. 1. Identify the current ntfs-3g version installed on the system using 'ntfs-3g --version' or your package manager
  2. 2. Update your package repository lists (e.g., 'apt update' for Debian-based systems)
  3. 3. Upgrade the ntfs-3g package to the latest available version in your distribution's repositories
  4. 4. Verify the installed version is 2021.8.22 or later using 'ntfs-3g --version'
  5. 5. If your distribution does not have 2021.8.22 or later available, consider compiling ntfs-3g from the official source at https://github.com/tuxera/ntfs-3g (version 2021.8.22 or later)
Caveat Minimal risk; upgrading to a newer stable version of NTFS-3G is a routine update with no expected breaking changes for normal NTFS mounting use cases

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-39263 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data