Security readout for executives and security teams
Plain-English summary
This flaw affects NTFS-3G before 2021.8.22 when handling crafted NTFS images. A malicious disk image or filesystem could trigger out-of-bounds reads. Business urgency is moderate: exploitation is local and requires high privileges, but systems that mount untrusted NTFS media or images should be prioritized.
Executive priority
Treat as a moderate-priority infrastructure hygiene issue. Patch systems that mount NTFS media, especially security, IT support, forensic, and virtualization environments. It is not KEV-listed in the source bundle, so emergency response is not supported by the provided evidence.
Technical view
CVE-2021-39258 is an input-validation issue in NTFS-3G before 2021.8.22. Crafted NTFS images can cause out-of-bounds reads in ntfs_attr_find and ntfs_external_attr_find. The CVSS vector is local, low complexity, high privileges, no user interaction, with high confidentiality, integrity, and availability impacts.
Likely exposure
Exposure is most likely on Linux or Unix-like systems using NTFS-3G to mount NTFS volumes, especially removable drives, forensic images, VM images, or other untrusted filesystem media. The source bundle does not identify specific downstream package versions beyond NTFS-3G before 2021.8.22.
Exploitation context
The source bundle does not show active exploitation, and KEV is false. The CVSS vector indicates local exploitation requiring high privileges and no user interaction. Practical risk is higher where privileged services or administrators mount NTFS images from external or untrusted sources.
Researcher notes
The provided affected-product metadata is incomplete, but the description identifies NTFS-3G before 2021.8.22. Analysis should focus on parser behavior around crafted NTFS attributes and external attributes. Do not infer remote attack paths from these sources; the CVSS vector is local with high privileges required.
Mitigation direction
- Upgrade NTFS-3G to 2021.8.22 or later where available.
- Apply Debian, Debian LTS, Gentoo, or other distribution security updates.
- Avoid mounting untrusted NTFS images or removable media on sensitive systems.
- Use vendor and distribution advisories to confirm the correct fixed package.
- Prioritize hosts that process external drives, forensic images, or VM disk images.
Validation and detection
- Inventory systems with NTFS-3G installed or bundled by the operating system.
- Confirm installed NTFS-3G versions are not earlier than 2021.8.22.
- Check distribution package changelogs against the cited Debian and Gentoo advisories.
- Review workflows where privileged users or services mount NTFS images.
- Verify remediation through package management records or approved asset scans.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-20: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-39258 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- 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
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.
CVSS vector scores
1 official scoreWe 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.
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H0.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.7MediumVector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/tuxera/ntfs-3g/releasesCVE reference
- https://github.com/tuxera/ntfs-3g/security/advisories/GHSA-q759-8j5v-q5jpCVE reference
- DSA-4971CVE reference · vendor-advisory
- [debian-lts-announce] 20211116 [SECURITY] [DLA 2819-1] ntfs-3g security updateCVE reference · mailing-list
- GLSA-202301-01CVE reference · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.