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CVE-2021-39261· NVD / CVE Program· CNA mitre

A crafted NTFS image can cause a heap-based buffer overflow in ntfs_compressed_pwrite in NTFS-3G < 2021.8.22.

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.45% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: ntfs-3g (Debian:10) 1:2017.3.23AR.3-3+deb10u1; ntfs-3g (Debian:11) 1:2017.3.23AR.3-4+deb11u1; ntfs-3g (Debian:12) 1:2021.8.22-2.

Low priority for now. Upgrade to ntfs-3g (Debian:10) 1:2017.3.23AR.3-3+deb10u1; ntfs-3g (Debian:11) 1:2017.3.23AR.3-4+deb11u1; ntfs-3g (Debian:12) 1:2021.8.22-2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Sep 7, 2021
Updated
Jun 17, 2026
EPSS
0.5% · 38th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-39261

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
tuxerantfs-3g
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux10.0
  • debian debian linux11.0
  • debian debian linux9.0
  • tuxera ntfs-3gbefore 2021.8.22

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:10ntfs-3gbefore 1:2017.3.23AR.3-3+deb10u11:2017.3.23AR.3-3+deb10u1
Debian:11ntfs-3gbefore 1:2017.3.23AR.3-4+deb11u11:2017.3.23AR.3-4+deb11u1
Debian:12ntfs-3gbefore 1:2021.8.22-21:2021.8.22-2
Debian:9ntfs-3gbefore 1:2016.2.22AR.1+dfsg-1+deb9u21:2016.2.22AR.1+dfsg-1+deb9u2
openSUSE:Leap 15.2ntfs-3g_ntfsprogsbefore 2021.8.22-lp152.5.3.12021.8.22-lp152.5.3.1
openSUSE:Leap 15.3ntfs-3g_ntfsprogsbefore 2021.8.22-3.8.12021.8.22-3.8.1
SUSE:Linux Enterprise Software Development Kit 12 SP5ntfs-3g_ntfsprogsbefore 2021.8.22-5.9.12021.8.22-5.9.1
SUSE:Linux Enterprise Workstation Extension 15 SP2ntfs-3g_ntfsprogsbefore 2021.8.22-3.8.12021.8.22-3.8.1

Same product

tuxera: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-40706In NTFS-3G 2022.10.3 before 2026.2.25, a heap buffer overflow exists in ntfs_build_permissions_posix() in acls.c that allows an attacker to
    33Monitor
  • CVE-2026-46570In NTFS-3G before 2026.7.7, a heap buffer overflow exists in ntfs_index_walk_down() in libntfs-3g/index.c that allows an attacker to corrupt
    32Monitor
  • CVE-2017-0358ntfs-3g: Modprobe influence vulnerability via environment variables
    32Monitor
  • CVE-2026-42616In NTFS-3G before 2026.7.7, a heap buffer overflow exists in cat() in ntfscat.c that allows an attacker to corrupt heap memory in the ntfsca
    31Monitor
  • CVE-2022-40284A buffer overflow was discovered in NTFS-3G before 2022.10.3.
    31Monitor
  • CVE-2022-30789A crafted NTFS image can cause a heap-based buffer overflow in ntfs_check_log_client_array in NTFS-3G through 2021.8.22.
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:ntfs-3g1:2021.8.22-2 · Debian:12Package registry (OSV)
opensuse:ntfs-3g_ntfsprogs2021.8.22-lp152.5.3.1 · openSUSE:Leap 15.2Package registry (OSV)
suse:ntfs-3g_ntfsprogs2021.8.22-5.9.1 · SUSE:Linux Enterprise Software Development Kit 12 SP5Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records