Linux Kernel: Use After Free (CVE-2026-23272)
Published Last modified Sources: Ubuntu, Siemens ProductCERT, Debian LTS, SUSE, Debian, BSI, CVE.org, EUVD, Msrc Update Guide
What is affected, what to do
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: unconditionally bump set->nelems before insertion In case that the set is full, a new element gets published then removed without waiting for the RCU grace period, while RCU reader can be walking over it already. To address this issue, add the element transaction even if set is full, but toggle the set_full flag to report -ENFILE so the abort path safely unwinds the set to its previous state.
The available sources name no fixed version. Check the vendor guidance in the references below.
Conflicting version data — version display is hidden until the data is resolved.
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Metrics
7.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
7.8
CVSS v3
Severity High on the scale from 0 to 10.
Source: Ubuntu, Siemens ProductCERT, Debian LTS, SUSE, Debian, BSI, CVE.org, EUVD, Msrc Update Guide
0.2 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 7.0
Show all metrics
- Severity
- High
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- 54.65 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- 7.8 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- 7.8
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- 0.2 %
- 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- 7.0
- Low — this CVE sits in the lower 10% of all CVEs scored today.
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: total
- Source: CISA Vulnrichment, as of 16 October 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-416
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- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
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
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: unconditionally bump set->nelems before insertion In case that the set is full, a new element gets published then removed without waiting for the RCU grace period, while RCU reader can be walking over it already. To address this issue, add the element transaction even if set is full, but toggle the set_full flag to report -ENFILE so the abort path safely unwinds the set to its previous state. As for element updates, decrement set->nelems to restore it. A simpler fix is to call synchronize_rcu() in the error path. However, with a large batch adding elements to already maxed-out set, this could cause noticeable slowdown of such batches.
Source: Ubuntu Security Notices, siemens_advisory, Debian LTS Advisories, suse_csaf, Debian Security Advisories, BSI WID Portal, BSI CSAF, cvelistv5, NVD (NIST), CVE.org (MITRE), ENISA EUVD, Microsoft Security Update Guide
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Linux | Linux |
|
|
| Siemens | SIMATIC S7 |
|
|
Vendors and products
Affected operating systems
| Linux | debian | linux | bookworm |
| Linux | debian | linux | trixie |
| Linux | debian | linux-6.1 | bullseye |
| Linux | linux | linux_kernel | 4.10 |
| Linux | linux | linux_kernel | 7.0 |
| Linux | linux | linux_kernel | — |
Weakness classes (CWE)
CWE-416Use After Free
Variant
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Entry at MITRE CWE-416
References & sources
- git.kernel.orgstable/c/e3ccb11fc8249759d23326038c8db987ddaabc77
- git.kernel.orgstable/c/86bc4b1a0f672d47ac19f9022432cb6a2e01cb33
- git.kernel.orgstable/c/6826131c7674329335ca25df2550163eb8a1fd0cPatch
- git.kernel.orgstable/c/ccb8c8f3c1127cf34d18c737309897c68046bf21Patch
- git.kernel.orgstable/c/def602e498a4f951da95c95b1b8ce8ae68aa733aPatch
- git.kernel.orgstable/c/25fcaef7948912652905e96922f36583a84fffed
- Siemens ProductCERTproductcert/html/ssa-784472.html
- git.kernel.orgstable/c/022effa9c54903858e443b1225370e6c758d03f6
- git.kernel.orgstable/c/25841e8d4241c6c3763e70ae95050f8108707b46
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 modifiedLinux
Show 3 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/2026/23xxx/CVE-2026-23272.json">CVE-2026-23272</a>Reference added —https://git.kernel.org/stable/c/022effa9c54903858e443b1225370e6c758d03f6Reference added —https://git.kernel.org/stable/c/25841e8d4241c6c3763e70ae95050f8108707b46Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Record modifiedCISA ADP
Weakness type: CWE-416
Show the original change
Individual changes of this event as published by NVD Type Action Before After Weakness type (CWE) added —CWE-416Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Record modifiedCISA ADP
CISA assessment (SSVC): exploitation: none known, automatable: no
Show the original change
Individual changes of this event as published by NVD Type Action Before After SSVC assessment added —{"id":"CVE-2026-23272","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:07:10.556223Z"}Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Record modifiedLinux
New references:- https://git.kernel.org/stable/c/25fcaef7948912652905e96922f36583a84fffed
- https://git.kernel.org/stable/c/6826131c7674329335ca25df2550163eb8a1fd0c
- https://git.kernel.org/stable/c/86bc4b1a0f672d47ac19f9022432cb6a2e01cb33
- https://git.kernel.org/stable/c/ccb8c8f3c1127cf34d18c737309897c68046bf21
and 2 more references
Show 15 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://git.kernel.org/stable/c/25fcaef7948912652905e96922f36583a84fffedReference added —https://git.kernel.org/stable/c/6826131c7674329335ca25df2550163eb8a1fd0cReference added —https://git.kernel.org/stable/c/86bc4b1a0f672d47ac19f9022432cb6a2e01cb33Reference added —https://git.kernel.org/stable/c/ccb8c8f3c1127cf34d18c737309897c68046bf21Reference added —https://git.kernel.org/stable/c/def602e498a4f951da95c95b1b8ce8ae68aa733aReference added —https://git.kernel.org/stable/c/e3ccb11fc8249759d23326038c8db987ddaabc77Reference removed https://git.kernel.org/stable/c/25fcaef7948912652905e96922f36583a84fffed—Reference removed https://git.kernel.org/stable/c/6826131c7674329335ca25df2550163eb8a1fd0c—Reference removed https://git.kernel.org/stable/c/86bc4b1a0f672d47ac19f9022432cb6a2e01cb33—Reference removed https://git.kernel.org/stable/c/ccb8c8f3c1127cf34d18c737309897c68046bf21—Reference removed https://git.kernel.org/stable/c/def602e498a4f951da95c95b1b8ce8ae68aa733a—Reference removed https://git.kernel.org/stable/c/e3ccb11fc8249759d23326038c8db987ddaabc77—Reference type removed https://git.kernel.org/stable/c/6826131c7674329335ca25df2550163eb8a1fd0c Types: Patch—Reference type removed https://git.kernel.org/stable/c/ccb8c8f3c1127cf34d18c737309897c68046bf21 Types: Patch—Reference type removed https://git.kernel.org/stable/c/def602e498a4f951da95c95b1b8ce8ae68aa733a Types: Patch—Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Record modifiedSiemens ADP
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/23xxx/CVE-2026-23272.json">CVE-2026-23272</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-784472.htmlSource identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
Show one older change
Record modifiedLinux
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://git.kernel.org/stable/c/25fcaef7948912652905e96922f36583a84fffedAffected versions (publisher) changed Linux, LinuxLinux, LinuxSource identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
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<a href="https://intel.neosec.eu/en/cve/CVE-2026-23272"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-23272.svg?lang=en" alt="CVE-2026-23272 – NEOSEC Intel" height="20"></a>