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Debian LinuxOperating system · Debian

CVE-2021-35266

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
In NTFS-3G versions < 2021.8.22, when a specially crafted NTFS inode pathname is supplied in an NTFS image a heap buffer overflow can occur resulting in memory disclosure, denial of service and even code execution.

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

NTFS-3G versions before 2021.8.22 contain a heap buffer overflow vulnerability when parsing specially crafted NTFS inode pathnames from NTFS images. This memory corruption flaw can lead to information disclosure, denial of service, and potentially arbitrary code execution.

MitigationUpgrade NTFS-3G to version 2021.8.22 or later to address the heap buffer overflow vulnerability. Validate that NTFS image handling operations continue to function correctly after the upgrade.

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. Identify NTFS-3G package version
    Run 'dpkg -l ntfs-3g' on Debian/Ubuntu or 'rpm -qi ntfs-3g' on Fedora/RHEL to retrieve the installed package version
    Affected if The displayed version is earlier than 2021.8.22 (for example, 1:1.2017.1-1 or similar older release numbers)
  2. Check NTFS-3G binary version directly
    Run 'ntfs-3g --version' to obtain the exact version string of the ntfs-3g binary
    Affected if The version number shown is less than 2021.8.22
  3. Identify actively mounted NTFS filesystems
    Run 'mount -t fuse' or 'mount | grep fuse' to list FUSE-mounted filesystems, or check '/etc/mtab' for NTFS entries using ntfs-3g
    Affected if Any NTFS partitions are currently mounted via the ntfs-3g driver on a vulnerable version
  4. Verify NTFS image file handling capability
    Check if tools like 'ntfs-3g' or 'ntfsclone' are installed and in use: run 'which ntfs-3g ntfsclone' and inspect running processes for NTFS image operations with 'ps aux | grep -i ntfs'
    Affected if NTFS-3G is installed and being used to mount or access NTFS images or partitions on a version before 2021.8.22

You are affected if NTFS-3G version is installed and it is earlier than 2021.8.22, and the system is actively using NTFS-3G to mount NTFS images or partitions.

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 address the heap buffer overflow vulnerability. Validate that NTFS image handling operations continue to function correctly after the upgrade.

Recommended fix High confidence

ntfs-3g version 2021.8.22 or later

  1. 1. Check the currently installed version of ntfs-3g: `ntfs-3g --version`
  2. 2. For Debian-based systems: Run `apt update` followed by `apt install ntfs-3g` to get the latest available version in the repositories
  3. 3. For Fedora systems: Run `dnf update ntfs-3g` to obtain the patched version
  4. 4. Verify the installed version is 2021.8.22 or later using `ntfs-3g --version`
  5. 5. If the distribution repositories do not have the fixed version, download ntfs-3g version 2021.8.22 or later from the official source: https://github.com/tuxera/ntfs-3g/releases and compile/install from source

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,920
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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-2021-35266 in production — separate from our analysis above.

No notes yet

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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