CVE-2026-43071

Boot-time kernel crash via single-bucket dentry hash

Published May 5, 2026 · Updated May 5, 2026

Out-of-bounds read in the Linux kernel dentry cache allows local users to crash the kernel when it boots with dhash_entries=1. dcache_init accepts a single hash bucket and sets d_hash_shift to 32, so d_hash performs an undefined 32-bit shift and __d_lookup dereferences an unallocated bucket. Setting the kernel boot parameter requires administrative control, and the demonstrated consequence is a boot-time page fault and kernel crash.

CVSS severity9.1
Critical
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in the Linux kernel dentry cache allows local users to crash the kernel when it boots with dhash_entries=1. dcache_init accepts a single hash bucket and sets d_hash_shift to 32, so d_hash performs an undefined 32-bit shift and __d_lookup dereferences an unallocated bucket. Setting the kernel boot parameter requires administrative control, and the demonstrated consequence is a boot-time page fault and kernel crash.

The record

CVE
CVE-2026-43071
Published
May 5, 2026
Updated
May 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-125, T1499
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. May 5, 2026CVE publishedPublication date reported by the CVE source.
  2. May 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <277cedabb0ab86baae83fa58218be13c6d3e5526
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <426ef05e82ee52c8d0e95fc0808b7383d8352d73
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5718df131ab78897a9dd1f2e71c3ba732d4392af
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <755b40903eff563768d4d96fd4ef51ec48adde3b
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ddd57ebce245f9c7e2f6902a6c087d6186d2385d
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f08fe8891c3eeb63b73f9f1f6d97aa629c821579

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <277cedabb0ab86baae83fa58218be13c6d3e5526; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <426ef05e82ee52c8d0e95fc0808b7383d8352d73; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5718df131ab78897a9dd1f2e71c3ba732d4392af; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <755b40903eff563768d4d96fd4ef51ec48adde3b; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ddd57ebce245f9c7e2f6902a6c087d6186d2385d; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f08fe8891c3eeb63b73f9f1f6d97aa629c821579

Published CVSS scores

9.1kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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