BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2023
CVE-2021-20251High confidence

A flaw was found in samba

Unknown · samba

5.9MediumCVSS 3.1
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 6 Mar 2025

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.76% for the current model date.

Compensating controls

  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Unknown samba and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  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: Within 30 daysRemediation target: Within 180 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 · sourcesambaVendor fix publishedDebian records a fixed source-package version for this release.2:4.17.2+dfsg-3Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcesambaVendor fix publishedDebian records a fixed source-package version for this release.2:4.17.2+dfsg-3Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcesambaVendor fix publishedDebian records a fixed source-package version for this release.2:4.17.2+dfsg-3Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcesambaVendor fix publishedDebian records a fixed source-package version for this release.2:4.17.2+dfsg-3Debian Security Tracker ↗Source updated 6 Oct 2026
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-2021-7689

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

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
01

What, why and how

A flaw was found in samba. A race condition in the password lockout code may lead to the risk of brute force attacks being successful if special conditions are met.

What

A flaw was found in samba. A race condition in the password lockout code may lead to the risk of brute force attacks being successful if special conditions are met.

Why

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

A flaw was found in samba. A race condition in the password lockout code may lead to the risk of brute force attacks being successful if special conditions are met.

Why

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. 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.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
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-362 ↗

CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition'). The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

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

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

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.IHighIntegrity impact: A successful attack can cause a major loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-362Public exploit reference
A

Official authority intelligence

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

BSI · German · WID-SEC-2022-1799Samba: Schwachstelle ermöglicht Umgehen von Sicherheitsvorkehrungen

Ein entfernter Angreifer kann eine Schwachstelle in Samba ausnutzen, um Sicherheitsvorkehrungen zu umgehen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20230308Security Bulletin 08 Mar 2023

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 08 Mar 2023, published on 8 March 2023. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0249Multiples vulnérabilités dans les produits IBM

VERecord?id=CVE-2016-4658 Référence CVE CVE-2016-9318 https://www.cve.org/CVERecord?id=CVE-2016-9318 Référence CVE CVE-2018-14040 https://www.cve.org/CVERecord?id=CVE-2018-14040 Référence CVE CVE-2018-14041 https://www.cve.org/CVERecord?id=CVE-2018-14041 Référence CVE CVE-2018-14042 https://www.cve.org/CVERecord?id=CVE-2018-14042 Référence CVE CVE-2018-5764 https://www.cve.org/CVERecord?id=CVE-2018-5764 Référence CVE CVE-2019-19921 https://www.cve.org/CVERecord?id=CVE-2019-19921 Référence CVE CVE-2019-8331 https://www.cve.org/CVERecord?id=CVE-2019-8331 Référence CVE CVE-2020-15115 https://www.cve.org/CVERecord?id=CVE-2020-15115 Référence CVE CVE-2021-20251 https://www.cve.org/CVERecord?id=CVE-2021-20251 Référence CVE CVE-2021-22569 https://www.cve.org/CVERecord?id=CVE-2021-22569 Référence CVE CVE-2021-22570 https://www.cve.org/CVERecord?id=CVE-2021-22570 Référence CVE CVE-2021-33036 https://www.cve.org/CVERecord?id=CVE-2021-33036 Référence CVE CVE-2021-37404 https://www.cve.org/CVERecord?id=CVE-2021-37404 Référence CVE CVE-2022-21426 https://www.cve.org/CVERecord?id=CVE-2022-21426 Référence CVE CVE-2022-21619 https://www.cve.org/CVERecord?id=CVE-2022-21619 Référence CVE CVE-2022-21624 https://www.cve.org/CVERecord?id=CVE-2022-21624 Référence CVE CVE-2022-21626 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-0969Multiples vulnérabilités dans les produits VMware

ecord?id=CVE-2020-35492 Référence CVE CVE-2020-8908 https://www.cve.org/CVERecord?id=CVE-2020-8908 Référence CVE CVE-2021-0561 https://www.cve.org/CVERecord?id=CVE-2021-0561 Référence CVE CVE-2021-20176 https://www.cve.org/CVERecord?id=CVE-2021-20176 Référence CVE CVE-2021-20241 https://www.cve.org/CVERecord?id=CVE-2021-20241 Référence CVE CVE-2021-20243 https://www.cve.org/CVERecord?id=CVE-2021-20243 Référence CVE CVE-2021-20244 https://www.cve.org/CVERecord?id=CVE-2021-20244 Référence CVE CVE-2021-20245 https://www.cve.org/CVERecord?id=CVE-2021-20245 Référence CVE CVE-2021-20246 https://www.cve.org/CVERecord?id=CVE-2021-20246 Référence CVE CVE-2021-20251 https://www.cve.org/CVERecord?id=CVE-2021-20251 Référence CVE CVE-2021-20266 https://www.cve.org/CVERecord?id=CVE-2021-20266 Référence CVE CVE-2021-20309 https://www.cve.org/CVERecord?id=CVE-2021-20309 Référence CVE CVE-2021-20310 https://www.cve.org/CVERecord?id=CVE-2021-20310 Référence CVE CVE-2021-20311 https://www.cve.org/CVERecord?id=CVE-2021-20311 Référence CVE CVE-2021-20312 https://www.cve.org/CVERecord?id=CVE-2021-20312 Référence CVE CVE-2021-20313 https://www.cve.org/CVERecord?id=CVE-2021-20313 Référence CVE CVE-2021-2161 https://www.cve.org/CVERecord?id=CVE-2021-2161 Référence CVE CVE-2021-2163 https://www.cve.org/CVERecord?id=CVE

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2023-004768Samba Project の Samba 他複数ベンダの製品における競合状態に関する脆弱性

Samba Project の Samba 他複数ベンダの製品には、競合状態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.
Fix not verified
Affected
samba: Samba 4.1 and newer
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 6 Mar 2023 · Last source change 6 Mar 2025, 15:49 UTC · CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVE recordCVE.org · 5.1
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-2021-7689
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
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 ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2021-7689↗CVE authority or vendor reference↗Public exploit 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-2021-20251 · cve.blacktree.nl