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Enterprise LinuxOperating system · Redhat

CVE-2021-33285

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 attribute is supplied to the function ntfs_get_attribute_value, a heap buffer overflow can occur allowing for memory disclosure or denial of service. The vulnerability is caused by an out-of-bound buffer access which can be triggered by mounting a crafted ntfs partition. The root cause is a missing consistency check after reading an MFT record : the "bytes_in_use" field should be less than the "bytes_allocated" field. When it is not, the parsing of the records proceeds into the wild.

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 in the ntfs_get_attribute_value function. The flaw is caused by a missing consistency check when parsing MFT records - the code fails to verify that the 'bytes_in_use' field is less than 'bytes_allocated', allowing an attacker to trigger out-of-bounds memory access by mounting a specially crafted NTFS partition.

MitigationUpgrade NTFS-3G to version 2021.8.22 or later. Avoid mounting untrusted NTFS partitions until the upgrade 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
Enterprise LinuxOperating system
Affected:= 7.0= 8.0
FedoraOperating system
Affected:= 33= 34= 35
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 'rpm -q ntfs-3g' on RHEL/Fedora or 'dpkg -l ntfs-3g' on Debian. Alternatively, run 'which ntfs-3g' or 'ntfs-3g --version'.
    Affected if The package or binary is present on the system
  2. Determine the installed NTFS-3G version
    Run 'ntfs-3g --version' or check the package version via 'rpm -q ntfs-3g' / 'dpkg -s ntfs-3g'. Compare the version number to the fixed release 2021.8.22.
    Affected if The installed version is earlier than 2021.8.22
  3. Check if NTFS kernel module is loaded
    Run 'lsmod | grep ntfs' to see if the ntfs kernel module is loaded, or check /proc/filesystems for ntfs fuseblk entries.
    Affected if NTFS support is available in the kernel or via FUSE
  4. Identify processes or services that mount NTFS partitions
    Review running processes for ntfs-3g usage via 'ps aux | grep ntfs', check /etc/fstab for NTFS entries, and review any automount or media mounting configurations.
    Affected if The system is configured to automatically mount NTFS partitions from external or untrusted sources
  5. Check for cron jobs or systemd units that mount NTFS
    Review /etc/cron* directories and systemd service/timer units for scripts or commands that invoke ntfs-3g or mount NTFS filesystems.
    Affected if Scheduled or triggered tasks exist that mount NTFS partitions

The system is affected if NTFS-3G version is installed and is earlier than 2021.8.22, and the system can mount NTFS partitions (including from external or untrusted sources).

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 NTFS partitions until the upgrade is applied.

Recommended fix High confidence

NTFS-3G version 2021.8.22 or later

  1. Check current NTFS-3G version installed: run `ntfs-3g --version`
  2. For Debian/Ubuntu: Run `apt-get update && apt-get install ntfs-3g` to install the latest version
  3. For Fedora: Run `dnf update ntfs-3g`
  4. For RHEL/CentOS: Run `yum update ntfs-3g` or enable EPEL repository and run `yum install ntfs-3g`
  5. Verify the fix by running `ntfs-3g --version` and confirming it shows version 2021.8.22 or later

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

Fix this in Enterprise Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing6.0 h
  • Review / QA3.0 h
16.0 hours of engineering $2,780
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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-2021-33285 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