CVE-2026-31429Public exploit

Kernel crash via KFENCE cache misclassification

Published Apr 20, 2026 · Updated Apr 20, 2026

Improper memory release in the Linux Kernel allows local users to crash the kernel through a crafted BPF test run when KFENCE is enabled. The skb_kfree_head() path misclassifies an exact-size KFENCE allocation by its skb_end_offset and returns it to skb_small_head_cache instead of its original kmalloc cache. Exploitation requires local low-privilege access, KFENCE, and a matching allocation size; the published impact is a kernel crash without confidentiality or integrity loss.

CVSS severity5.5
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper memory release in the Linux Kernel allows local users to crash the kernel through a crafted BPF test run when KFENCE is enabled. The skb_kfree_head() path misclassifies an exact-size KFENCE allocation by its skb_end_offset and returns it to skb_small_head_cache instead of its original kmalloc cache. Exploitation requires local low-privilege access, KFENCE, and a matching allocation size; the published impact is a kernel crash without confidentiality or integrity loss.

The record

CVE
CVE-2026-31429
Published
Apr 20, 2026
Updated
Apr 20, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-401, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 20, 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=6.3
  2. Affected versionversion=bf9f1baa279f0758dc2297080360c5a616843927 <0f42e3f4fe2a58394e37241d02d9ca6ab7b7d516
  3. Affected versionversion=bf9f1baa279f0758dc2297080360c5a616843927 <2d64618ea846d8d033477311f805ca487d6a6696
  4. Affected versionversion=bf9f1baa279f0758dc2297080360c5a616843927 <474e00b935db250cac320d10c1d3cf4e44b46721
  5. Affected versionversion=bf9f1baa279f0758dc2297080360c5a616843927 <60313768a8edc7094435975587c00c2d7b834083

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.3; version=bf9f1baa279f0758dc2297080360c5a616843927 <0f42e3f4fe2a58394e37241d02d9ca6ab7b7d516; version=bf9f1baa279f0758dc2297080360c5a616843927 <2d64618ea846d8d033477311f805ca487d6a6696; version=bf9f1baa279f0758dc2297080360c5a616843927 <474e00b935db250cac320d10c1d3cf4e44b46721; version=bf9f1baa279f0758dc2297080360c5a616843927 <60313768a8edc7094435975587c00c2d7b834083

Published CVSS scores

6.6Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.6Oracle LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499Endpoint Denial of Service

Public exploit references

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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