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CVE Record

CVE-2021-39263: A crafted NTFS image can trigger a heap-based buffer overflow, caused by an unsanitized attribute in ntfs_g...

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.

MediumCVSS 6.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-39263 is a memory-safety flaw in NTFS-3G before 2021.8.22. A specially crafted NTFS filesystem image can trigger a heap-based buffer overflow. Business risk is mainly on systems that mount or analyze untrusted NTFS media or images.

Executive priority

Treat as a moderate operational security item. Patch exposed systems during normal security maintenance, sooner where teams process external disks, forensic images, or removable media.

Technical view

The issue is caused by unsanitized attribute handling in ntfs_get_attribute_value, leading to heap-based buffer overflow when processing crafted NTFS images. CVSS 3.1 is 6.7 with local attack vector, low complexity, high privileges required, no user interaction, and high confidentiality, integrity, and availability impact.

Likely exposure

Exposure is most likely on Linux or Unix-like systems using NTFS-3G before 2021.8.22, especially forensic, backup, desktop, removable-media, or image-processing workflows that handle NTFS content.

Exploitation context

The source bundle does not show active exploitation, and KEV is false. The CVSS vector indicates local access with high privileges is required, but successful exploitation could have high impact on the affected host.

Researcher notes

Evidence identifies NTFS-3G before 2021.8.22 and the affected function. Product metadata in the bundle is incomplete, so distribution-specific package names and fixed builds should be verified through vendor advisories.

Mitigation direction

  • Upgrade NTFS-3G to 2021.8.22 or later.
  • Apply relevant Debian, Debian LTS, or Gentoo security updates.
  • Restrict mounting or processing of untrusted NTFS images.
  • Follow current vendor package guidance for your distribution.
  • Prioritize systems that handle removable media or disk images.

Validation and detection

  • Inventory installed NTFS-3G package versions.
  • Confirm versions are not older than 2021.8.22.
  • Check distro security advisories for fixed package status.
  • Identify workflows that mount untrusted NTFS media.
  • Review controls limiting local privileged mounting activity.
Prepared
Confidence
high
Sources
7

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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-2021-39263 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
6Source 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-2021-39263Attack 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.

CWE-20 · source CWE mapping

Improper Input Validation

Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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