Samba: vfs_worm does not block directory modification (CVE-2026-2340)
Published Last modified Sources: Debian LTS, SUSE, Red Hat, Ubuntu, Debian, BSI, CVE.org, EUVD
What is affected, what to do
A flaw was found in Samba’s vfs_worm module. The module is intended to provide write-once, read-many (WORM) protections by preventing modification of files after a configurable grace period.
Update Red Hat Enterprise Linux 10 to version 0:4.23.5-109.el10_2, Red Hat Enterprise Linux 10.0 Extended Update Support to version 0:4.21.3-114.el10_0.1, Red Hat Enterprise Linux 8 to version 0:4.19.4-16.el8_10.
- Affected
- Red Hat Enterprise Linux 10
lt *..0:4.23.5-109.el10_2 - Red Hat Enterprise Linux 10.0 Extended Update Support
lt *..0:4.21.3-114.el10_0.1 - Red Hat Enterprise Linux 8
lt *..0:4.19.4-16.el8_10 - Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
lt *..0:4.15.5-16.el8_6.1 - Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
lt *..0:4.15.5-16.el8_6.1 - Red Hat Enterprise Linux 8.8 Telecommunications Update Service
lt *..0:4.17.5-7.el8_8.1 - Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
lt *..0:4.17.5-7.el8_8.1 - Red Hat Enterprise Linux 9
lt *..0:4.23.5-10.el9_8 - Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
lt *..0:4.17.5-105.el9_2.5 - Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
lt *..0:4.19.4-105.el9_4.4 - Red Hat Enterprise Linux 9.6 Extended Update Support
lt *..0:4.21.3-14.el9_6.1 - Red Hat OpenShift Container Platform 4.12
lt *..412.86.202608241157-0 - Red Hat OpenShift Container Platform 4.12
lt *..412.86.202609082051-0 - Red Hat OpenShift Container Platform 4.13
lt *..413.92.202609080414-0 - Red Hat OpenShift Container Platform 4.13
lt *..413.92.202609302032-0 - Red Hat OpenShift Container Platform 4.14
lt *..414.92.202608172040-0 - Red Hat OpenShift Container Platform 4.14
lt *..414.92.202609011250-0 - Red Hat OpenShift Container Platform 4.15
lt *..415.92.202608180329-0 - Red Hat OpenShift Container Platform 4.15
lt *..415.92.202609140326-0 - Red Hat OpenShift Container Platform 4.16
lt *..416.94.202608150307-0 - Red Hat OpenShift Container Platform 4.16
lt *..416.94.202609011112-0 - Red Hat OpenShift Container Platform 4.17
lt *..417.94.202608250221-0 - Red Hat OpenShift Container Platform 4.17
lt *..417.94.202609191027-0 - Red Hat OpenShift Container Platform 4.18
lt *..418.94.202608142238-0 - Red Hat OpenShift Container Platform 4.18
lt *..418.94.202609031320-0 - Red Hat OpenShift Container Platform 4.19
lt *..4.19.9.6.202606241344-0
- Red Hat Enterprise Linux 10
- Fixed in
- Red Hat Enterprise Linux 10
0:4.23.5-109.el10_2 - Red Hat Enterprise Linux 10.0 Extended Update Support
0:4.21.3-114.el10_0.1 - Red Hat Enterprise Linux 8
0:4.19.4-16.el8_10 - Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
0:4.15.5-16.el8_6.1 - Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
0:4.15.5-16.el8_6.1 - Red Hat Enterprise Linux 8.8 Telecommunications Update Service
0:4.17.5-7.el8_8.1 - Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
0:4.17.5-7.el8_8.1 - Red Hat Enterprise Linux 9
0:4.23.5-10.el9_8 - Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
0:4.17.5-105.el9_2.5 - Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
0:4.19.4-105.el9_4.4 - Red Hat Enterprise Linux 9.6 Extended Update Support
0:4.21.3-14.el9_6.1 - Red Hat OpenShift Container Platform 4.12
412.86.202608241157-0 - Red Hat OpenShift Container Platform 4.12
412.86.202609082051-0 - Red Hat OpenShift Container Platform 4.13
413.92.202609080414-0 - Red Hat OpenShift Container Platform 4.13
413.92.202609302032-0 - Red Hat OpenShift Container Platform 4.14
414.92.202608172040-0 - Red Hat OpenShift Container Platform 4.14
414.92.202609011250-0 - Red Hat OpenShift Container Platform 4.15
415.92.202608180329-0 - Red Hat OpenShift Container Platform 4.15
415.92.202609140326-0 - Red Hat OpenShift Container Platform 4.16
416.94.202608150307-0 - Red Hat OpenShift Container Platform 4.16
416.94.202609011112-0 - Red Hat OpenShift Container Platform 4.17
417.94.202608250221-0 - Red Hat OpenShift Container Platform 4.17
417.94.202609191027-0 - Red Hat OpenShift Container Platform 4.18
418.94.202608142238-0 - Red Hat OpenShift Container Platform 4.18
418.94.202609031320-0 - Red Hat OpenShift Container Platform 4.19
4.19.9.6.202606241344-0
- Red Hat Enterprise Linux 10
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Metrics
6.5
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
6.5
CVSS v3
Severity Medium on the scale from 0 to 10.
Source: Debian LTS, SUSE, Red Hat, Ubuntu, Debian, BSI, CVE.org, EUVD
0.9 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 60.8
Show all metrics
- Severity
- Medium
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 80.09 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 6.5 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 6.5
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.9 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 60.8
- High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
- CISA assessment (SSVC)
- Exploitation: none known · not automatable · Technical impact: partial
- Source: CISA Vulnrichment, as of 29 May 2026
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-280
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
A flaw was found in Samba’s vfs_worm module. The module is intended to provide write-once, read-many (WORM) protections by preventing modification of files after a configurable grace period. Due to insufficient validation during rename operations, an authenticated user with write access to a share could overwrite a protected file by renaming a newly created file over the existing WORM-protected file.
Source: Debian LTS Advisories, suse_csaf, redhat_csaf, Ubuntu Security Notices, Debian Security Advisories, BSI WID Portal, BSI CSAF, cvelistv5, NVD (NIST), CVE.org (MITRE), ENISA EUVD
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 |
|
|
| Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support |
|
|
| Red Hat | Red Hat Enterprise Linux 6 |
|
|
| Red Hat | Red Hat Enterprise Linux 7 |
|
|
| Red Hat | Red Hat Enterprise Linux 8 |
|
|
| Red Hat | Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support |
|
|
| Red Hat | Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On |
|
|
| Red Hat | Red Hat Enterprise Linux 8.8 Telecommunications Update Service |
|
|
| Red Hat | Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions |
|
|
| Red Hat | Red Hat Enterprise Linux 9 |
|
|
| Red Hat | Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions |
|
|
| Red Hat | Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions |
|
|
| Red Hat | Red Hat Enterprise Linux 9.6 Extended Update Support |
|
|
| Red Hat | Red Hat OpenShift Container Platform 4.12 |
|
|
| Red Hat | Red Hat OpenShift Container Platform 4.13 |
|
|
| Red Hat | Red Hat OpenShift Container Platform 4.14 |
|
|
| Red Hat | Red Hat OpenShift Container Platform 4.15 |
|
|
| Red Hat | Red Hat OpenShift Container Platform 4.16 |
|
|
| Red Hat | Red Hat OpenShift Container Platform 4.17 |
|
|
| Red Hat | Red Hat OpenShift Container Platform 4.18 |
|
|
| Red Hat | Red Hat OpenShift Container Platform 4.19 |
|
|
| redhat | openshift_container_platform |
|
|
| samba | samba |
|
|
| Open Source | Samba |
|
|
Vendors and products
- Debian Samba
- Open Source Samba
- Red Hat Red Hat Enterprise Linux 10
- Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
- Red Hat Red Hat Enterprise Linux 6
- Red Hat Red Hat Enterprise Linux 7
- Red Hat Red Hat Enterprise Linux 8
- Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
- Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-life Add-on
- Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
- Red Hat Red Hat Enterprise Linux 8.8 Update Services For Sap Solutions
- Red Hat Red Hat Enterprise Linux 9
Affected operating systems
| Linux | redhat | enterprise_linux | 10.0 |
| Linux | redhat | enterprise_linux | 7.0 |
| Linux | redhat | enterprise_linux | 8.0 |
| Linux | redhat | enterprise_linux | 9.0 |
| Linux | debian | samba | bookworm |
| Linux | debian | samba | bullseye |
| Linux | debian | samba | trixie |
Weakness classes (CWE)
CWE-280Improper Handling of Insufficient Permissions or Privileges
Base
The product does not handle or incorrectly handles when it has insufficient privileges to access resources or functionality as specified by their permissions. This may cause it to follow unexpected code paths that may leave the product in an invalid state.
Entry at MITRE CWE-280
References & sources
- access.redhat.comRHSA-2026:22644Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:22963Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:25049Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:25979Vendor advisory, x_refsource_REDHAT
- access.redhat.comsecurity/cve/CVE-2026-2340Vulnerability database, x_refsource_REDHAT
- bugzilla.redhat.comRHBZ#2447318Issue tracking, x_refsource_REDHAT
- bugzilla.samba.orgshow_bug.cgi?id=15997
- access.redhat.comRHSA-2026:28053Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:28054Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:28055Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:28056Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:28057Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:29863Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:57483Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:56786Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:56853Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:56911Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:59831Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:60019Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:62549Vendor advisory, x_refsource_REDHAT
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:77320Source identifier: secalert@redhat.com
Record modifiedRed Hat
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:70586Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:67857Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:65839Source identifier: secalert@redhat.com
Show 14 older changes
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:65907Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:65851Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:62409Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:62549Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:59831Source identifier: secalert@redhat.com
Record modifiedRed Hat
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Source identifier: secalert@redhat.com
Record modifiedRed Hat
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Source identifier: secalert@redhat.com
Record modifiedRed Hat
Show 4 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:56786Reference added —https://access.redhat.com/errata/RHSA-2026:56853Reference added —https://access.redhat.com/errata/RHSA-2026:56911Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/2xxx/CVE-2026-2340.json">CVE-2026-2340</a>Reference added —https://access.redhat.com/errata/RHSA-2026:57483Source identifier: secalert@redhat.com
Record modifiedRed Hat
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) changed Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8 (+14)Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8 (+15)Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://access.redhat.com/errata/RHSA-2026:29863Affected versions (publisher) changed Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8 (+14)Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8 (+14)Source identifier: secalert@redhat.com
Record modifiedRed Hat
Show 4 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://access.redhat.com/errata/RHSA-2026:28054Reference added —https://access.redhat.com/errata/RHSA-2026:28055Reference added —https://access.redhat.com/errata/RHSA-2026:28056Affected versions (publisher) changed Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 8 (+9)Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8 (+13)Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show the original change
Individual changes of this event as published by NVD Type Action Before After Reference added —https://access.redhat.com/errata/RHSA-2026:25979Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show the original change
Individual changes of this event as published by NVD Type Action Before After Reference added —https://access.redhat.com/errata/RHSA-2026:25049Source identifier: secalert@redhat.com
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<a href="https://intel.neosec.eu/en/cve/CVE-2026-2340"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-2340.svg?lang=en" alt="CVE-2026-2340 – NEOSEC Intel" height="20"></a>