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CVE-2021-33285: In NTFS-3G versions < 2021.8.22, when a specially crafted NTFS attribute is supplied to the function ntfs_g...

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.

MediumCVSS 6.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-33285 affects NTFS-3G before 2021.8.22. A malicious NTFS filesystem can trigger a heap buffer overflow when mounted, potentially causing data exposure or denial of service. The main business risk is from systems that mount untrusted NTFS media or disk images.

Executive priority

Treat this as a moderate-priority hygiene fix unless the organization regularly handles untrusted storage media or forensic disk images. In those environments, prioritize faster patching and stricter mount controls.

Technical view

The flaw is an out-of-bounds buffer access in ntfs_get_attribute_value after parsing an inconsistent MFT record. Missing validation allows bytes_in_use to exceed bytes_allocated, so record parsing proceeds past expected bounds. CVSS 3.1 is 6.7 with local attack vector and high privileges required.

Likely exposure

Exposure is most likely on Linux or Unix systems using NTFS-3G to mount NTFS partitions, removable drives, or disk images. Risk is higher where privileged users, services, or workflows mount untrusted storage content.

Exploitation context

The source bundle does not indicate active exploitation, and KEV status is false. Exploitation requires a crafted NTFS partition being mounted in an affected NTFS-3G version, with the CVSS vector indicating local access and high privileges.

Researcher notes

The core validation target is NTFS-3G record parsing around MFT consistency checks, specifically bytes_in_use versus bytes_allocated. Public sources name memory disclosure and denial of service impacts, but do not provide evidence of active exploitation in this bundle.

Mitigation direction

  • Upgrade NTFS-3G to 2021.8.22 or a vendor-fixed package.
  • Apply relevant Debian, Fedora, Gentoo, or distribution security updates.
  • Restrict mounting of untrusted NTFS media and disk images.
  • Review automount behavior on endpoints and servers using NTFS-3G.
  • Check vendor guidance for supported fixed versions.

Validation and detection

  • Inventory systems with NTFS-3G installed and record package versions.
  • Confirm affected systems are not running versions before 2021.8.22.
  • Identify workflows that mount external NTFS media or disk images.
  • Verify distribution security advisories are applied to managed images.
  • Review recent crash reports linked to NTFS mounting activity.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-20: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-33285 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
6.7 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
10Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
6.7CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H0.85.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

6.7Medium
CVSS 3.1 vector shape for CVE-2021-33285Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

CWE-20

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.