Security readout for executives and security teams
Plain-English summary
CVE-2021-39259 affects NTFS-3G before 2021.8.22. A specially crafted NTFS filesystem image can cause out-of-bounds memory access. Business risk is mainly to Linux systems that mount NTFS drives or disk images, especially where untrusted media is handled.
Executive priority
Prioritize patching in environments that routinely handle removable drives, customer media, disk images, or forensic evidence. For general servers that do not mount NTFS filesystems, urgency is lower but cleanup should remain in normal vulnerability remediation cycles.
Technical view
The flaw is an input-validation issue in ntfs_inode_lookup_by_name where an unsanitized NTFS attribute length can trigger out-of-bounds access. The CVSS vector is local, low complexity, high privileges required, no user interaction, with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely on Linux or Unix-like systems with NTFS-3G installed and used to mount NTFS filesystems. Workstations, forensic systems, file-processing hosts, and removable-media workflows deserve attention. The bundle does not provide CPEs or a complete product matrix.
Exploitation context
The provided sources do not establish active exploitation, and the CVE is not marked as KEV. Exploitation requires local access and high privileges per CVSS, plus interaction with a crafted NTFS image. Treat it as a controlled-entry risk rather than an internet-exposed service issue.
Researcher notes
Evidence points to CWE-20 input validation failure in NTFS-3G before 2021.8.22. The source bundle names the vulnerable function but does not include exploit details, proof of exploitation, or exhaustive downstream package status. Validate against distro package changelogs rather than upstream version alone.
Mitigation direction
- Upgrade NTFS-3G to 2021.8.22 or later where available.
- Apply fixed distribution packages from Debian, Gentoo, or your platform vendor.
- Restrict mounting of untrusted NTFS media and disk images.
- Use least-privilege workflows for removable media and forensic image handling.
- Check current vendor guidance before deploying compensating controls.
Validation and detection
- Inventory systems with ntfs-3g installed.
- Confirm installed NTFS-3G versions are 2021.8.22 or vendor-fixed builds.
- Identify workflows that mount NTFS removable media or images.
- Review package manager security advisories for ntfs-3g fixes.
- Confirm operational controls prevent untrusted NTFS mounts by privileged users.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
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 lookupCVE-2021-39259 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.