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CVE Record

CVE-2021-39252: A crafted NTFS image can cause an out-of-bounds read in ntfs_ie_lookup in NTFS-3G < 2021.8.22.

A crafted NTFS image can cause an out-of-bounds read in ntfs_ie_lookup 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-2021-39252 affects NTFS-3G before 2021.8.22. A malicious NTFS filesystem image can trigger an out-of-bounds read in ntfs_ie_lookup. The CVSS vector requires local access with high privileges, but the rated impact includes confidentiality, integrity, and availability.

Executive priority

Treat this as a targeted operational hygiene issue, not an emergency internet-facing incident. Prioritize patching systems that process removable media or disk images, especially admin workstations, forensic environments, and servers where privileged users mount NTFS content.

Technical view

The flaw is described as improper input validation leading to out-of-bounds read in ntfs_ie_lookup when parsing a crafted NTFS image. It is tracked as CWE-125 and CWE-20, with CVSS 3.1 score 6.7 and vector AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.

Likely exposure

Exposure is most likely on systems that have NTFS-3G installed and may mount or inspect untrusted NTFS images, removable media, or disk images. The source bundle names NTFS-3G versions before 2021.8.22, plus Debian, Fedora, and Gentoo security updates.

Exploitation context

The CVE source bundle does not show CISA KEV listing or cited evidence of active exploitation. Exploitation requires a crafted NTFS image and local high privileges per the CVSS vector, so business urgency depends on who can provide or mount filesystem images.

Researcher notes

Evidence is limited to the CVE record and vendor advisories in the supplied bundle. The affected CPE data is not populated, so rely on NTFS-3G version and distribution package status rather than CPE matching alone. Do not assume broader product impact beyond NTFS-3G.

Mitigation direction

  • Upgrade NTFS-3G to 2021.8.22 or a vendor-fixed distribution package.
  • Apply relevant Debian, Fedora, Gentoo, or other vendor security updates.
  • Limit handling of untrusted NTFS images and removable media on sensitive systems.
  • Review vendor advisories for package-specific fixed versions and backports.

Validation and detection

  • Inventory systems with NTFS-3G installed or bundled in operational images.
  • Confirm installed versions are 2021.8.22 or vendor-patched builds.
  • Identify workflows that mount NTFS images, external drives, or forensic media.
  • Check vulnerability scanners against distro advisory fixed package versions.
Prepared
Confidence
high
Sources
9

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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-125: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cwe · low confidence lookup

CWE-20: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2021-39252 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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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
8Source 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-2021-39252Attack 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-125CWE-20

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