BlackTreeCVE Intelligence
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Full vulnerability report · 2021
CVE-2021-39261High confidence

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

Unknown · Unknown

7.8HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Medium, lowered one band.downgradedsince 5 Dec 2025

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 0.45% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

4 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcentfs-3gVendor fix publishedDebian records a fixed source-package version for this release.1:2021.8.22-2Debian Security Tracker ↗Source updated 23 Oct 2026
Debian bookwormbookworm · sourcentfs-3gVendor fix publishedDebian records a fixed source-package version for this release.1:2021.8.22-2Debian Security Tracker ↗Source updated 23 Oct 2026
Debian forkyforky · sourcentfs-3gVendor fix publishedDebian records a fixed source-package version for this release.1:2021.8.22-2Debian Security Tracker ↗Source updated 23 Oct 2026
Debian sidsid · sourcentfs-3gVendor fix publishedDebian records a fixed source-package version for this release.1:2021.8.22-2Debian Security Tracker ↗Source updated 23 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2021-39261 · CSAF 2.0 · revision 23 · interimSUSE Product Security TeamCVE-2021-39261
146 recommended

The vendor recommends these product versions as the target state.

  • libntfs-3g-devel-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP2
  • libntfs-3g87-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP2
  • ntfs-3g-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP2
  • ntfsprogs-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP2
  • libntfs-3g-devel-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP3
  • libntfs-3g87-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP3
  • ntfs-3g-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP3
  • ntfsprogs-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP3
  • libntfs-3g-devel-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP4
  • libntfs-3g87-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP4
  • ntfs-3g-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP4
  • ntfsprogs-2021.8.22-3.8.1 as component of SUSE Linux Enterprise Desktop 15 SP4
Summary
A crafted NTFS image can cause a heap-based buffer overflow in ntfs_compressed_pwrite in NTFS-3G < 2021.8.22.
Remediation
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-25623

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

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

What

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

Why

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

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

Why

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
local access → Improper Input Validation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Local
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-20 ↗

CWE-20: Improper Input Validation. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
CWE-20
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2022-1728Red Enterprise Linux Advanced Virtualization: Mehrere Schwachstellen

Ein entfernter oder lokaler, authentisierter Angreifer kann mehrere Schwachstellen in Red Enterprise Linux Advanced Virtualization ausnutzen, um einen Denial of Service zu verursachen, Sicherheitsvorkehrungen zu umgehen, beliebigen Code auszuführen und Informationen offenzulegen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20210908Security Bulletin 08 Sep 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 08 Sep 2021, published on 8 September 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-011636NTFS-3G における境界外書き込みに関する脆弱性

NTFS-3G には、境界外書き込みに関する脆弱性が存在します。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
n/a
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 7 Sept 2021 · Last source change 5 Dec 2025, 14:54 UTC · CWE-20 · Improper Input Validation

CVE recordCVE.org · 5.2
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-25623
Product sourceUnavailable
Remediation sourceVendor CSAF · SUSE Product Security Team
CWE sourceCISA ADP
NVD statusNVD modified after enrichment

Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Remediation statusRemediation status changed from Awaiting fix to Mitigation available.
    Before
    Awaiting fix
    After
    Mitigation available
    SUSE Product Security Team ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Remediation guidance recorded
ENISA EUVD · EUVD-2021-25623↗SUSE Product Security Team security advisory↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-39261 · cve.blacktree.nl