dbcve.org
Debian LinuxOperating system · Debian

CVE-2021-39254

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 cause an integer overflow in memmove, leading to a heap-based buffer overflow in the function ntfs_attr_record_resize, 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 specially crafted NTFS image triggers an integer overflow in memmove, which leads to a heap-based buffer overflow in the ntfs_attr_record_resize function in NTFS-3G versions prior to 2021.8.22. The vulnerability allows potential code execution or denial of service when mounting a malicious NTFS volume.

MitigationUpgrade NTFS-3G to version 2021.8.22 or later. Avoid mounting untrusted or unknown NTFS images until the patch is applied.

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
FedoraOperating system
Affected:= 33= 35
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 NTFS-3G package version
    Run `ntfs-3g --version` or check your package manager (dpkg -l ntfs-3g or rpm -q ntfs-3g)
    Affected if The version displayed is earlier than 2021.8.22 or the package is not found at the latest version
  2. Verify ntfs-3g binary exists
    Check if the ntfs-3g binary is present: `which ntfs-3g` or `ls -l /sbin/mount.ntfs*`
    Affected if The ntfs-3g binary is present and outdated
  3. Identify NTFS mounting capability
    Check if the system uses NTFS-3G for mounting: examine /proc/filesystems for ntfs and check mount utility capabilities
    Affected if NTFS support is enabled via ntfs-3g and the version is vulnerable

You are affected if NTFS-3G version is below 2021.8.22 and the system can mount NTFS volumes using this tool.

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. Avoid mounting untrusted or unknown NTFS images until the patch is applied.

Recommended fix High confidence

NTFS-3G >= 2021.8.22

  1. 1. Check the current NTFS-3G version installed on the system using 'ntfs-3g --version' or the package manager.
  2. 2. For Debian-based systems (Debian 9, 10, 11): Run 'sudo apt-get update' followed by 'sudo apt-get install ntfs-3g' to upgrade to the latest available version in the repositories, or download and install NTFS-3G version 2021.8.22 or later from source.
  3. 3. For Fedora systems (33, 35): Run 'sudo dnf update ntfs-3g' to upgrade to the latest version including the fix.
  4. 4. For Gentoo systems: Run 'sudo emerge --sync' and then 'sudo emerge -av sys-fs/ntfs3g' to upgrade to the patched version.
  5. 5. After upgrade, verify the installed version is 2021.8.22 or later using 'ntfs-3g --version'.
  6. 6. Recreate any NTFS mounts to ensure the updated library is loaded.

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
20.0 hours of engineering $3,440
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Scan for this in your stack

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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-2021-39254 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