Linux Kernel: security vulnerability (CVE-2026-43071)
Published Last modified Sources: Siemens ProductCERT, Ubuntu, Debian LTS, CVE.org, EUVD, BSI
What is affected, what to do
In the Linux kernel, the following vulnerability has been resolved: dcache: Limit the minimal number of bucket to two There is an OOB read problem on dentry_hashtable when user sets 'dhash_entries=1': BUG: unable to handle page fault for address: ffff888b30b774b0 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Oops: Oops: 0000 [#1] SMP PTI RIP: 0010:__d_lookup+0x56/0x120 Call Trace: d_lookup.cold+0x16/0x5d lookup_dcache+0x27/0xf0 lookup_one_qstr_excl+0x2a/0x180 start_dirop+0x55/0xa0 simple_start_creating+0x8d/0xa0 debugfs_start_creating+0x8c/0x180 debugfs_create_dir+0x1d/0x1c0 pinctrl_init+0x6d/0x140 do_one_initcall+0x6d/0x3d0 kernel_init_freeable+0x39f/0x460 kernel_init+0x2a/0x260 There will be only one bucket in dentry_hashtable when dhash_entries is set as one, and d_hash_shift is calculated as 32 by dcache_init(). Then, following process will access more than one buckets(which memory region is not allocated) in dentry_hashtable: d_lookup b = d_hash(hash) dentry_hashtable + ((u32)hashlen >> d_hash_shift) // The C standard defines the behavior of right shift amounts // exceeding the bit width of the operand as undefined.
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
9.1
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
9.1
CVSS v3
Severity Critical on the scale from 0 to 10.
Source: Siemens ProductCERT, Ubuntu, Debian LTS, CVE.org, EUVD, BSI
0.5 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 39.8
Show all metrics
- Severity
- Critical
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- 75.08 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- 9.1 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- 9.1
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- 0.5 %
- 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- 39.8
- 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 · automatable · Technical impact: partial
- 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-125
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: dcache: Limit the minimal number of bucket to two There is an OOB read problem on dentry_hashtable when user sets 'dhash_entries=1': BUG: unable to handle page fault for address: ffff888b30b774b0 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Oops: Oops: 0000 [#1] SMP PTI RIP: 0010:__d_lookup+0x56/0x120 Call Trace: d_lookup.cold+0x16/0x5d lookup_dcache+0x27/0xf0 lookup_one_qstr_excl+0x2a/0x180 start_dirop+0x55/0xa0 simple_start_creating+0x8d/0xa0 debugfs_start_creating+0x8c/0x180 debugfs_create_dir+0x1d/0x1c0 pinctrl_init+0x6d/0x140 do_one_initcall+0x6d/0x3d0 kernel_init_freeable+0x39f/0x460 kernel_init+0x2a/0x260 There will be only one bucket in dentry_hashtable when dhash_entries is set as one, and d_hash_shift is calculated as 32 by dcache_init(). Then, following process will access more than one buckets(which memory region is not allocated) in dentry_hashtable: d_lookup b = d_hash(hash) dentry_hashtable + ((u32)hashlen >> d_hash_shift) // The C standard defines the behavior of right shift amounts // exceeding the bit width of the operand as undefined. The // result of '(u32)hashlen >> d_hash_shift' becomes 'hashlen', // so 'b' will point to an unallocated memory region. hlist_bl_for_each_entry_rcu(b) hlist_bl_first_rcu(head) h->first // read OOB! Fix it by limiting the minimal number of dentry_hashtable bucket to two, so that 'd_hash_shift' won't exceeds the bit width of type u32.
Source: siemens_advisory, Ubuntu Security Notices, Debian LTS Advisories, cvelistv5, NVD (NIST), ENISA EUVD, CVE.org (MITRE), BSI WID Portal, BSI CSAF
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 |
|
|
| Microsoft | Azure Linux |
|
|
| Siemens | SIMATIC S7 |
|
|
Vendors and products
Affected operating systems
| Linux | debian | linux | bookworm |
| Linux | debian | linux-6.1 | bullseye |
| Linux | linux | linux_kernel | 3.17 |
| Linux | linux | linux_kernel | — |
Weakness classes (CWE)
CWE-125Out-of-bounds Read
Base
The product reads data past the end, or before the beginning, of the intended buffer.
Entry at MITRE CWE-125
References & sources
- git.kernel.orgstable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73euvd, Patch
- git.kernel.orgstable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385deuvd, Patch
- git.kernel.orgstable/c/755b40903eff563768d4d96fd4ef51ec48adde3beuvd, Patch
- git.kernel.orgstable/c/5718df131ab78897a9dd1f2e71c3ba732d4392afeuvd, Patch
- git.kernel.orgstable/c/277cedabb0ab86baae83fa58218be13c6d3e5526euvd, Patch
- git.kernel.orgstable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579euvd, Patch
- git.kernel.orgstable/c/45b06bb5ea96f75ad81d7ef446f832ea6b0026fePatch
- Siemens ProductCERTproductcert/html/ssa-019113.html
- Siemens ProductCERTproductcert/html/ssa-457936.html
- Siemens ProductCERTproductcert/html/ssa-784472.html
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 modifiedCISA ADP
Weakness type: CWE-125
Show the original change
Individual changes of this event as published by NVD Type Action Before After Weakness type (CWE) added —CWE-125Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Record modifiedCISA ADP
CISA assessment (SSVC): exploitation: none known, automatable: yes
Show the original change
Individual changes of this event as published by NVD Type Action Before After SSVC assessment added —{"id":"CVE-2026-43071","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:14:19.375972Z"}Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Record modifiedSiemens ADP
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/2026/43xxx/CVE-2026-43071.json">CVE-2026-43071</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-457936.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-784472.htmlSource identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
Record modifiedLinux
New references:- https://git.kernel.org/stable/c/277cedabb0ab86baae83fa58218be13c6d3e5526
- https://git.kernel.org/stable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73
- https://git.kernel.org/stable/c/45b06bb5ea96f75ad81d7ef446f832ea6b0026fe
- https://git.kernel.org/stable/c/5718df131ab78897a9dd1f2e71c3ba732d4392af
and 3 more references
Show 21 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://git.kernel.org/stable/c/277cedabb0ab86baae83fa58218be13c6d3e5526Reference added —https://git.kernel.org/stable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73Reference added —https://git.kernel.org/stable/c/45b06bb5ea96f75ad81d7ef446f832ea6b0026feReference added —https://git.kernel.org/stable/c/5718df131ab78897a9dd1f2e71c3ba732d4392afReference added —https://git.kernel.org/stable/c/755b40903eff563768d4d96fd4ef51ec48adde3bReference added —https://git.kernel.org/stable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385dReference added —https://git.kernel.org/stable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579Reference removed https://git.kernel.org/stable/c/277cedabb0ab86baae83fa58218be13c6d3e5526—Reference removed https://git.kernel.org/stable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73—Reference removed https://git.kernel.org/stable/c/45b06bb5ea96f75ad81d7ef446f832ea6b0026fe—Reference removed https://git.kernel.org/stable/c/5718df131ab78897a9dd1f2e71c3ba732d4392af—Reference removed https://git.kernel.org/stable/c/755b40903eff563768d4d96fd4ef51ec48adde3b—Reference removed https://git.kernel.org/stable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385d—Reference removed https://git.kernel.org/stable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579—Reference type removed https://git.kernel.org/stable/c/277cedabb0ab86baae83fa58218be13c6d3e5526 Types: Patch—Reference type removed https://git.kernel.org/stable/c/426ef05e82ee52c8d0e95fc0808b7383d8352d73 Types: Patch—Reference type removed https://git.kernel.org/stable/c/45b06bb5ea96f75ad81d7ef446f832ea6b0026fe Types: Patch—Reference type removed https://git.kernel.org/stable/c/5718df131ab78897a9dd1f2e71c3ba732d4392af Types: Patch—Reference type removed https://git.kernel.org/stable/c/755b40903eff563768d4d96fd4ef51ec48adde3b Types: Patch—Reference type removed https://git.kernel.org/stable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385d Types: Patch—Reference type removed https://git.kernel.org/stable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579 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/2026/43xxx/CVE-2026-43071.json">CVE-2026-43071</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-019113.htmlSource identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
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