BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2024
CVE-2023-52522High confidence

net: fix possible store tearing in neigh_periodic_work()

Linux · Linux

8.8HighCVSS 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 1 structured product or package state 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:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.34% 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 Linux Linux 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: 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.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 1 structured product or package state 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.6.5.8-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.6.1.64-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.6.5.8-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.6.5.8-1Debian 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
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-2023-57147

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 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

In the Linux kernel, the following vulnerability has been resolved: net: fix possible store tearing in neigh_periodic_work() While looking at a related syzbot report involving neigh_periodic_work(), I found that I forgot to add an annotation when deleting an RCU protected item from a list. Readers use rcu_deference(*np), we need to use either rcu_assign_pointer() or WRITE_ONCE() on writer side to prevent store tearing. I use rcu_assign_pointer() to have lockdep support, this was the choice made in neigh_flush_dev().

What

In the Linux kernel, the following vulnerability has been resolved: net: fix possible store tearing in neigh_periodic_work() While looking at a related syzbot report involving neigh_periodic_work(), I found that I forgot to add an annotation when deleting an RCU protected item from a list. Readers use rcu_deference(*np), we need to use either rcu_assign_pointer() or WRITE_ONCE() on writer side to prevent store tearing. I use rcu_assign_pointer() to have lockdep support, this was the choice made in neigh_flush_dev().

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through an adjacent network 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

In the Linux kernel, the following vulnerability has been resolved: net: fix possible store tearing in neigh_periodic_work() While looking at a related syzbot report involving neigh_periodic_work(), I found that I forgot to add an annotation when deleting an RCU protected item from a list. Readers use rcu_deference(*np), we need to use either rcu_assign_pointer() or WRITE_ONCE() on writer side to prevent store tearing. I use rcu_assign_pointer() to have lockdep support, this was the choice made in neigh_flush_dev().

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through an adjacent network 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.
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
an adjacent network → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Adjacent
Privileges required
None: unauthenticated exploitation is possible
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.
CWE not yet assigned
CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:A/AC:L/PR:N/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.

AVAdjacentAttack vector: The attacker must be on an adjacent or logically close network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.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.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
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.
Unauthenticated
A

Official authority intelligence

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

BSI · German · WID-SEC-2024-1226Red Hat OpenShift: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Red Hat OpenShift ausnutzen, um Dateien zu manipulieren, einen Denial-of-Service-Zustand zu verursachen, beliebigen Code auszuführen, vertrauliche Informationen offenzulegen, seine Privilegien zu erweitern oder um weitere nicht spezifizierte Angriffe auszuführen.

Official advisory ↗
BSI · German · WID-SEC-2024-0534Linux Kernel: Mehrere Schwachstellen

Ein lokaler Angreifer kann mehrere Schwachstellen im Linux-Kernel ausnutzen, um einen Denial-of-Service-Zustand herbeizuführen oder einen nicht spezifizierten Angriff durchzuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20240306Security Bulletin 06 Mar 2024

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 06 Mar 2024, published on 6 March 2024. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1165Multiples vulnérabilités dans les produits IBM

d?id=CVE-2023-52463 Référence CVE CVE-2023-52464 https://www.cve.org/CVERecord?id=CVE-2023-52464 Référence CVE CVE-2023-52469 https://www.cve.org/CVERecord?id=CVE-2023-52469 Référence CVE CVE-2023-52470 https://www.cve.org/CVERecord?id=CVE-2023-52470 Référence CVE CVE-2023-52471 https://www.cve.org/CVERecord?id=CVE-2023-52471 Référence CVE CVE-2023-52476 https://www.cve.org/CVERecord?id=CVE-2023-52476 Référence CVE CVE-2023-52478 https://www.cve.org/CVERecord?id=CVE-2023-52478 Référence CVE CVE-2023-52486 https://www.cve.org/CVERecord?id=CVE-2023-52486 Référence CVE CVE-2023-52492 https://www.cve.org/CVERecord?id=CVE-2023-52492 Référence CVE CVE-2023-52522 https://www.cve.org/CVERecord?id=CVE-2023-52522 Référence CVE CVE-2023-52530 https://www.cve.org/CVERecord?id=CVE-2023-52530 Référence CVE CVE-2023-52560 https://www.cve.org/CVERecord?id=CVE-2023-52560 Référence CVE CVE-2023-52615 https://www.cve.org/CVERecord?id=CVE-2023-52615 Référence CVE CVE-2023-52619 https://www.cve.org/CVERecord?id=CVE-2023-52619 Référence CVE CVE-2023-52622 https://www.cve.org/CVERecord?id=CVE-2023-52622 Référence CVE CVE-2023-52623 https://www.cve.org/CVERecord?id=CVE-2023-52623 Référence CVE CVE-2023-52626 https://www.cve.org/CVERecord?id=CVE-2023-52626 Référence CVE CVE-2023-52648 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-0211Multiples vulnérabilités dans le noyau Linux d'Ubuntu

https://ubuntu.com/security/notices/USN-7328-2 Bulletin de sécurité Ubuntu USN-7332-3 du 13 mars 2025 https://ubuntu.com/security/notices/USN-7332-3 Bulletin de sécurité Ubuntu USN-7344-2 du 13 mars 2025 https://ubuntu.com/security/notices/USN-7344-2 Référence CVE CVE-2021-47103 https://www.cve.org/CVERecord?id=CVE-2021-47103 Référence CVE CVE-2021-47606 https://www.cve.org/CVERecord?id=CVE-2021-47606 Référence CVE CVE-2022-48772 https://www.cve.org/CVERecord?id=CVE-2022-48772 Référence CVE CVE-2022-48994 https://www.cve.org/CVERecord?id=CVE-2022-48994 Référence CVE CVE-2023-52488 https://www.cve.org/CVERecord?id=CVE-2023-52488 Référence CVE CVE-2023-52522 https://www.cve.org/CVERecord?id=CVE-2023-52522 Référence CVE CVE-2023-52799 https://www.cve.org/CVERecord?id=CVE-2023-52799 Référence CVE CVE-2023-52818 https://www.cve.org/CVERecord?id=CVE-2023-52818 Référence CVE CVE-2023-52880 https://www.cve.org/CVERecord?id=CVE-2023-52880 Référence CVE CVE-2024-23848 https://www.cve.org/CVERecord?id=CVE-2024-23848 Référence CVE CVE-2024-26685 https://www.cve.org/CVERecord?id=CVE-2024-26685 Référence CVE CVE-2024-35896 https://www.cve.org/CVERecord?id=CVE-2024-35896 Référence CVE CVE-2024-36886 https://www.cve.org/CVERecord?id=CVE-2024-36886 Référence CVE CVE-2024-36952 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-0185Multiples vulnérabilités dans le noyau Linux d'Ubuntu

tin de sécurité Ubuntu USN-7323-2 du 06 mars 2025 https://ubuntu.com/security/notices/USN-7323-2 Référence CVE CVE-2021-47103 https://www.cve.org/CVERecord?id=CVE-2021-47103 Référence CVE CVE-2021-47469 https://www.cve.org/CVERecord?id=CVE-2021-47469 Référence CVE CVE-2021-47606 https://www.cve.org/CVERecord?id=CVE-2021-47606 Référence CVE CVE-2022-48994 https://www.cve.org/CVERecord?id=CVE-2022-48994 Référence CVE CVE-2022-49034 https://www.cve.org/CVERecord?id=CVE-2022-49034 Référence CVE CVE-2023-52458 https://www.cve.org/CVERecord?id=CVE-2023-52458 Référence CVE CVE-2023-52488 https://www.cve.org/CVERecord?id=CVE-2023-52488 Référence CVE CVE-2023-52522 https://www.cve.org/CVERecord?id=CVE-2023-52522 Référence CVE CVE-2023-52799 https://www.cve.org/CVERecord?id=CVE-2023-52799 Référence CVE CVE-2023-52818 https://www.cve.org/CVERecord?id=CVE-2023-52818 Référence CVE CVE-2023-52880 https://www.cve.org/CVERecord?id=CVE-2023-52880 Référence CVE CVE-2023-52913 https://www.cve.org/CVERecord?id=CVE-2023-52913 Référence CVE CVE-2023-52917 https://www.cve.org/CVERecord?id=CVE-2023-52917 Référence CVE CVE-2024-26685 https://www.cve.org/CVERecord?id=CVE-2024-26685 Référence CVE CVE-2024-26718 https://www.cve.org/CVERecord?id=CVE-2024-26718 Référence CVE CVE-2024-35887 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0998Multiples vulnérabilités dans le noyau Linux de Red Hat

ulletin de sécurité Red Hat RHSA-2024:9497 du 13 novembre 2024 https://access.redhat.com/errata/RHSA-2024:9497 Bulletin de sécurité Red Hat RHSA-2024:9498 du 13 novembre 2024 https://access.redhat.com/errata/RHSA-2024:9498 Bulletin de sécurité Red Hat RHSA-2024:9500 du 13 novembre 2024 https://access.redhat.com/errata/RHSA-2024:9500 Bulletin de sécurité Red Hat RHSA-2024:9546 du 13 novembre 2024 https://access.redhat.com/errata/RHSA-2024:9546 Bulletin de sécurité Red Hat RHSA-2024:9605 du 14 novembre 2024 https://access.redhat.com/errata/RHSA-2024:9605 Référence CVE CVE-2022-48695 https://www.cve.org/CVERecord?id=CVE-2022-48695 Référence CVE CVE-2023-52522 https://www.cve.org/CVERecord?id=CVE-2023-52522 Référence CVE CVE-2023-52749 https://www.cve.org/CVERecord?id=CVE-2023-52749 Référence CVE CVE-2024-26640 https://www.cve.org/CVERecord?id=CVE-2024-26640 Référence CVE CVE-2024-26656 https://www.cve.org/CVERecord?id=CVE-2024-26656 Référence CVE CVE-2024-26772 https://www.cve.org/CVERecord?id=CVE-2024-26772 Référence CVE CVE-2024-26837 https://www.cve.org/CVERecord?id=CVE-2024-26837 Référence CVE CVE-2024-26870 https://www.cve.org/CVERecord?id=CVE-2024-26870 Référence CVE CVE-2024-26906 https://www.cve.org/CVERecord?id=CVE-2024-26906 Référence CVE CVE-2024-26984 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0821Multiples vulnérabilités dans le noyau Linux de Red Hat

d?id=CVE-2022-48754 Référence CVE CVE-2022-48760 https://www.cve.org/CVERecord?id=CVE-2022-48760 Référence CVE CVE-2022-48804 https://www.cve.org/CVERecord?id=CVE-2022-48804 Référence CVE CVE-2022-48836 https://www.cve.org/CVERecord?id=CVE-2022-48836 Référence CVE CVE-2022-48866 https://www.cve.org/CVERecord?id=CVE-2022-48866 Référence CVE CVE-2023-52439 https://www.cve.org/CVERecord?id=CVE-2023-52439 Référence CVE CVE-2023-52470 https://www.cve.org/CVERecord?id=CVE-2023-52470 Référence CVE CVE-2023-52476 https://www.cve.org/CVERecord?id=CVE-2023-52476 Référence CVE CVE-2023-52478 https://www.cve.org/CVERecord?id=CVE-2023-52478 Référence CVE CVE-2023-52522 https://www.cve.org/CVERecord?id=CVE-2023-52522 Référence CVE CVE-2023-52605 https://www.cve.org/CVERecord?id=CVE-2023-52605 Référence CVE CVE-2023-52683 https://www.cve.org/CVERecord?id=CVE-2023-52683 Référence CVE CVE-2023-52817 https://www.cve.org/CVERecord?id=CVE-2023-52817 Référence CVE CVE-2023-52840 https://www.cve.org/CVERecord?id=CVE-2023-52840 Référence CVE CVE-2023-52880 https://www.cve.org/CVERecord?id=CVE-2023-52880 Référence CVE CVE-2023-52884 https://www.cve.org/CVERecord?id=CVE-2023-52884 Référence CVE CVE-2023-6040 https://www.cve.org/CVERecord?id=CVE-2023-6040 Référence CVE CVE-2024-2201 https://www.cve.org/CVERecord?id=CVE

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0364Multiples vulnérabilités dans le noyau Linux de RedHat

d?id=CVE-2023-45863 Référence CVE CVE-2023-46862 https://www.cve.org/CVERecord?id=CVE-2023-46862 Référence CVE CVE-2023-51043 https://www.cve.org/CVERecord?id=CVE-2023-51043 Référence CVE CVE-2023-51779 https://www.cve.org/CVERecord?id=CVE-2023-51779 Référence CVE CVE-2023-51780 https://www.cve.org/CVERecord?id=CVE-2023-51780 Référence CVE CVE-2023-52434 https://www.cve.org/CVERecord?id=CVE-2023-52434 Référence CVE CVE-2023-52448 https://www.cve.org/CVERecord?id=CVE-2023-52448 Référence CVE CVE-2023-52476 https://www.cve.org/CVERecord?id=CVE-2023-52476 Référence CVE CVE-2023-52489 https://www.cve.org/CVERecord?id=CVE-2023-52489 Référence CVE CVE-2023-52522 https://www.cve.org/CVERecord?id=CVE-2023-52522 Référence CVE CVE-2023-52529 https://www.cve.org/CVERecord?id=CVE-2023-52529 Référence CVE CVE-2023-52574 https://www.cve.org/CVERecord?id=CVE-2023-52574 Référence CVE CVE-2023-52578 https://www.cve.org/CVERecord?id=CVE-2023-52578 Référence CVE CVE-2023-52580 https://www.cve.org/CVERecord?id=CVE-2023-52580 Référence CVE CVE-2023-52581 https://www.cve.org/CVERecord?id=CVE-2023-52581 Référence CVE CVE-2023-52610 https://www.cve.org/CVERecord?id=CVE-2023-52610 Référence CVE CVE-2023-52620 https://www.cve.org/CVERecord?id=CVE-2023-52620 Référence CVE CVE-2023-6040 https://www.cve.org/CVERecord?id=C

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2023-029752Linux の Linux Kernel における脆弱性

Linux の Linux Kernel には、不特定の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 availability varies by product
Affected
Linux: 767e97e1e0db0d0f3152cd2f3bd3403596aedbad < 95eabb075a5902f4c0834ab1fb12dc35730c05af, 767e97e1e0db0d0f3152cd2f3bd3403596aedbad < 2ea52a2fb8e87067e26bbab4efb8872639240eb0, 767e97e1e0db0d0f3152cd2f3bd3403596aedbad < 147d89ee41434b97043c2dcb17a97dc151859baa, 767e97e1e0db0d0f3152cd2f3bd3403596aedbad < f82aac8162871e87027692b36af335a2375d4580, 767e97e1e0db0d0f3152cd2f3bd3403596aedbad < a75152d233370362eebedb2643592e7c883cc9fc, 767e97e1e0db0d0f3152cd2f3bd3403596aedbad < 25563b581ba3a1f263a00e8c9a97f5e7363be6fd, 2.6.37
Fixed
Linux: < 2.6.37, 5.4.258 ≤ 5.4.*, 5.10.198 ≤ 5.10.*, 5.15.135 ≤ 5.15.*, 6.1.57 ≤ 6.1.*, 6.5.7 ≤ 6.5.*, 6.6 ≤ *
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 2 Mar 2024 · Last source change 5 Aug 2026, 09:10 UTC · CWE not yet assigned

CVE recordCVE.org · 5.2
CVSS sourceCNA
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-2023-57147
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceUnavailable
NVD statusNVD modified after enrichment

Missing structured fields: CWE classification. 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
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-2023-52522 · cve.blacktree.nl