BlackTreeCVE Intelligence
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Full vulnerability report · 2021
CVE-2021-3506High confidence

An out-of-bounds (OOB) memory access flaw was found in fs/f2fs/node.c in the f2fs module in the Linux kernel in versions before 5.12.0-rc4

Unknown · kernel

Official source article: Siemens SSA-354112 ↗. Check the applicable product and release in the original source.

7.1HighCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 27 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Medium, lowered one band.downgradedsince 3 Aug 2024

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 0.37% 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 kernel 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.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 27 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

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

5 package states
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 1 affected package state shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

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 · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.5.10.38-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.5.10.38-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.5.10.38-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.5.10.38-1Debian Security Tracker ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-raspi-realtimeAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 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.

2 current
CVE-2021-3506 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitykernel: Out of bounds memory access bug in get_next_net_page() in fs/f2fs/node.c
197 known not affected

The vendor explicitly states that these products are not affected by this CVE.

  • kernel as a component of Red Hat Enterprise Linux 6
  • kernel-abi-whitelists as a component of Red Hat Enterprise Linux 6
  • kernel-bootwrapper as a component of Red Hat Enterprise Linux 6
  • kernel-debug as a component of Red Hat Enterprise Linux 6
  • kernel-debug-devel as a component of Red Hat Enterprise Linux 6
  • kernel-devel as a component of Red Hat Enterprise Linux 6
  • kernel-doc as a component of Red Hat Enterprise Linux 6
  • kernel-firmware as a component of Red Hat Enterprise Linux 6
  • kernel-headers as a component of Red Hat Enterprise Linux 6
  • kernel-kdump as a component of Red Hat Enterprise Linux 6
  • kernel-kdump-devel as a component of Red Hat Enterprise Linux 6
  • kernel.src as a component of Red Hat Enterprise Linux 6
Summary
An out-of-bounds (OOB) memory access flaw was found in fs/f2fs/node.c in the f2fs module in the Linux kernel. A bounds check failure allows a local attacker to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability.
Remediation
No remediation text is recorded.
SSA-354112 · CSAF 2.0 · revision 1 · interimSiemens ProductCERTSSA-354112: Multiple Vulnerabilities in SCALANCE M-800 Family Before V8.2
26 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • RUGGEDCOM RM1224 LTE(4G) EU (6GK6108-4AM00-2BA2)
  • RUGGEDCOM RM1224 LTE(4G) NAM (6GK6108-4AM00-2DA2)
  • SCALANCE M804PB (6GK5804-0AP00-2AA2)
  • SCALANCE M812-1 ADSL-Router (6GK5812-1AA00-2AA2)
  • SCALANCE M812-1 ADSL-Router (6GK5812-1BA00-2AA2)
  • SCALANCE M816-1 ADSL-Router (6GK5816-1AA00-2AA2)
  • SCALANCE M816-1 ADSL-Router (6GK5816-1BA00-2AA2)
  • SCALANCE M826-2 SHDSL-Router (6GK5826-2AB00-2AB2)
  • SCALANCE M874-2 (6GK5874-2AA00-2AA2)
  • SCALANCE M874-3 (6GK5874-3AA00-2AA2)
  • SCALANCE M874-3 3G-Router (CN) (6GK5874-3AA00-2FA2)
  • SCALANCE M876-3 (6GK5876-3AA02-2BA2)
Summary
An out-of-bounds (OOB) memory access flaw was found in fs/f2fs/node.c in the f2fs module in the Linux kernel in versions before 5.12.0-rc4. A bounds check failure allows a local attacker to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability.
Remediation
Update to V8.2 or later version
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-2021-26825

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 actionPatch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 27 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

An out-of-bounds (OOB) memory access flaw was found in fs/f2fs/node.c in the f2fs module in the Linux kernel in versions before 5.12.0-rc4. A bounds check failure allows a local attacker to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability.

What

An out-of-bounds (OOB) memory access flaw was found in fs/f2fs/node.c in the f2fs module in the Linux kernel in versions before 5.12.0-rc4. A bounds check failure allows a local attacker to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability.

Why

The product reads data past the end, or before the beginning, of the intended buffer.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.

What

An out-of-bounds (OOB) memory access flaw was found in fs/f2fs/node.c in the f2fs module in the Linux kernel in versions before 5.12.0-rc4. A bounds check failure allows a local attacker to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability.

Why

The product reads data past the end, or before the beginning, of the intended buffer.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.

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 → Out-of-bounds Read → disrupt the affected service
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-125 ↗

CWE-125: Out-of-bounds Read. The product reads data past the end, or before the beginning, of the intended buffer.

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:N/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.INoneIntegrity impact: No direct loss is represented by this metric.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.
Denial of serviceCWE-125
A

Official authority intelligence

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

Cyber Security Agency of Singapore · English · CSA-SB-20210421Security Bulletin 21 Apr 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 21 Apr 2021, published on 21 April 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0968Multiples vulnérabilités dans les produits Siemens

De multiples vulnérabilités ont été découvertes dans les produits Siemens. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, un déni de service à distance et une atteinte à la confidentialité des données.

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-265Multiples vulnérabilités dans le noyau Linux de Ubuntu

ord?id=CVE-2021-28715 Référence CVE CVE-2021-28972 https://www.cve.org/CVERecord?id=CVE-2021-28972 Référence CVE CVE-2021-29650 https://www.cve.org/CVERecord?id=CVE-2021-29650 Référence CVE CVE-2021-32399 https://www.cve.org/CVERecord?id=CVE-2021-32399 Référence CVE CVE-2021-33033 https://www.cve.org/CVERecord?id=CVE-2021-33033 Référence CVE CVE-2021-33034 https://www.cve.org/CVERecord?id=CVE-2021-33034 Référence CVE CVE-2021-33098 https://www.cve.org/CVERecord?id=CVE-2021-33098 Référence CVE CVE-2021-34693 https://www.cve.org/CVERecord?id=CVE-2021-34693 Référence CVE CVE-2021-3483 https://www.cve.org/CVERecord?id=CVE-2021-3483 Référence CVE CVE-2021-3506 https://www.cve.org/CVERecord?id=CVE-2021-3506 Référence CVE CVE-2021-3564 https://www.cve.org/CVERecord?id=CVE-2021-3564 Référence CVE CVE-2021-3573 https://www.cve.org/CVERecord?id=CVE-2021-3573 Référence CVE CVE-2021-3612 https://www.cve.org/CVERecord?id=CVE-2021-3612 Référence CVE CVE-2021-3679 https://www.cve.org/CVERecord?id=CVE-2021-3679 Référence CVE CVE-2021-38160 https://www.cve.org/CVERecord?id=CVE-2021-38160 Référence CVE CVE-2021-38198 https://www.cve.org/CVERecord?id=CVE-2021-38198 Référence CVE CVE-2021-38204 https://www.cve.org/CVERecord?id=CVE-2021-38204 Référence CVE CVE-2021-38208 https://www.cve.org/CVERecord?id=CVE-2021-

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-552Multiples vulnérabilités dans le noyau Linux d'Ubuntu

De multiples vulnérabilités ont été découvertes dans le noyau Linux d'Ubuntu. Elles permettent à un attaquant de provoquer une exécution de code arbitraire, un déni de service et une atteinte à la confidentialité des données.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-492Multiples vulnérabilités dans le noyau Linux d'Ubuntu

De multiples vulnérabilités ont été découvertes dans le noyau Linux d'Ubuntu. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire, un déni de service et une atteinte à l'intégrité des données.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-482Multiples vulnérabilités dans le noyau Linux de Debian LTS

ecord?id=CVE-2021-29647 Référence CVE CVE-2021-29650 https://www.cve.org/CVERecord?id=CVE-2021-29650 Référence CVE CVE-2021-30002 https://www.cve.org/CVERecord?id=CVE-2021-30002 Référence CVE CVE-2021-31829 https://www.cve.org/CVERecord?id=CVE-2021-31829 Référence CVE CVE-2021-31916 https://www.cve.org/CVERecord?id=CVE-2021-31916 Référence CVE CVE-2021-32399 https://www.cve.org/CVERecord?id=CVE-2021-32399 Référence CVE CVE-2021-33034 https://www.cve.org/CVERecord?id=CVE-2021-33034 Référence CVE CVE-2021-3428 https://www.cve.org/CVERecord?id=CVE-2021-3428 Référence CVE CVE-2021-3483 https://www.cve.org/CVERecord?id=CVE-2021-3483 Référence CVE CVE-2021-3506 https://www.cve.org/CVERecord?id=CVE-2021-3506 Référence CVE CVE-2021-3564 https://www.cve.org/CVERecord?id=CVE-2021-3564 Référence CVE CVE-2021-3573 https://www.cve.org/CVERecord?id=CVE-2021-3573 Référence CVE CVE-2021-3587 https://www.cve.org/CVERecord?id=CVE-2021-3587 Gestion détaillée du document le 24 juin 2021 Version initiale Alertes Avis Bulletins d’actualités Mentions légales Conditions générales À propos Contact cyber.gouv.fr service-public.fr legifrance.gouv.fr info.gouv.fr france.fr info.gouv.fr/risques Premier Ministre / Secrétariat Général de la Défense et de la Sécurité Nationale / Agence nationale de la sécurité des systèmes

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-483Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2020-26147 Référence CVE CVE-2021-23133 https://www.cve.org/CVERecord?id=CVE-2021-23133 Référence CVE CVE-2021-23134 https://www.cve.org/CVERecord?id=CVE-2021-23134 Référence CVE CVE-2021-29155 https://www.cve.org/CVERecord?id=CVE-2021-29155 Référence CVE CVE-2021-31440 https://www.cve.org/CVERecord?id=CVE-2021-31440 Référence CVE CVE-2021-31829 https://www.cve.org/CVERecord?id=CVE-2021-31829 Référence CVE CVE-2021-32399 https://www.cve.org/CVERecord?id=CVE-2021-32399 Référence CVE CVE-2021-33034 https://www.cve.org/CVERecord?id=CVE-2021-33034 Référence CVE CVE-2021-33200 https://www.cve.org/CVERecord?id=CVE-2021-33200 Référence CVE CVE-2021-3506 https://www.cve.org/CVERecord?id=CVE-2021-3506 Référence CVE CVE-2021-3543 https://www.cve.org/CVERecord?id=CVE-2021-3543 Référence CVE CVE-2021-3600 https://www.cve.org/CVERecord?id=CVE-2021-3600 Référence CVE CVE-2021-3609 https://www.cve.org/CVERecord?id=CVE-2021-3609 Gestion détaillée du document le 24 juin 2021 Version initiale Alertes Avis Bulletins d’actualités Mentions légales Conditions générales À propos Contact cyber.gouv.fr service-public.fr legifrance.gouv.fr info.gouv.fr france.fr info.gouv.fr/risques Premier Ministre / Secrétariat Général de la Défense et de la Sécurité Nationale / Agence nationale de la sécurité des systèmes

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-005924Linux Kernel における境界外読み取りに関する脆弱性

Linux Kernel には、境界外読み取りに関する脆弱性が存在します。

Official advisory ↗
NCSC-NL · Dutch · NCSC-2024-0433Kwetsbaarheden verholpen in Siemens producten

De kwetsbaarheden stellen een kwaadwillende mogelijk in staat aanvallen uit te voeren die kunnen leiden tot de volgende categorieën schade: - Denial-of-Service (DoS) - Cross-Site-Scripting (XSS) - Manipulatie van gegevens - Omzeilen van een beveiligingsmaatregel - Omzeilen van authenticatie - (Remote) code execution (Administrator/Root rechten) - (Remote) code execution (Gebruikersrechten) - Toegang tot systeemgegevens - Verhoogde gebruikersrechten De kwaadwillende heeft hiervoor toegang nodig tot de productieomgeving. Het is goed gebruik een dergelijke omgeving niet publiek toegankelijk te hebben.

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 availability varies by product
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 19 Apr 2021 · Last source change 3 Aug 2024, 16:53 UTC · CWE-125 · Out-of-bounds Read

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-2021-26825
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCNA
NVD statusNVD enriched

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
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2021-26825↗Vendor CSAF · Siemens ProductCERT · Siemens SSA-354112↗Patch or update reference↗Patch or update reference↗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-2021-3506 · cve.blacktree.nl