CVE-2025-38255

Kernel crash via zero-group pointer dereference

Published Jul 9, 2025 · Updated May 11, 2026

NULL pointer dereference in Linux 6.3 and later affected branches allows local users to crash the kernel through null_blk configfs. group_cpus_evenly() passes a zero group count to kcalloc(), receives ZERO_SIZE_PTR, and later dereferences it while remapping null_blk queues. The demonstrated path requires privileged configfs access and setting poll_queues to zero, causing a kernel panic and host service interruption.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux 6.3 and later affected branches allows local users to crash the kernel through null_blk configfs. group_cpus_evenly() passes a zero group count to kcalloc(), receives ZERO_SIZE_PTR, and later dereferences it while remapping null_blk queues. The demonstrated path requires privileged configfs access and setting poll_queues to zero, causing a kernel panic and host service interruption.

The record

CVE
CVE-2025-38255
Published
Jul 9, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jul 9, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=6a6dcae8f486c3f3298d0767d34505121c7b0b81 <29d39e0d5f16c060e32542b2cf351c09fd22b250
  3. Affected versionversion=6a6dcae8f486c3f3298d0767d34505121c7b0b81 <64a99eff8dcf1f951a544e6058341b2b19a8fdbd
  4. Affected versionversion=6a6dcae8f486c3f3298d0767d34505121c7b0b81 <911ef2e8a7de5b2bae8ff11fb0bd01f699e6db65
  5. Affected versionversion=6a6dcae8f486c3f3298d0767d34505121c7b0b81 <df831e97739405ecbaddb85516bc7d4d1c933d6b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=6.3; version=6a6dcae8f486c3f3298d0767d34505121c7b0b81 <29d39e0d5f16c060e32542b2cf351c09fd22b250; version=6a6dcae8f486c3f3298d0767d34505121c7b0b81 <64a99eff8dcf1f951a544e6058341b2b19a8fdbd; version=6a6dcae8f486c3f3298d0767d34505121c7b0b81 <911ef2e8a7de5b2bae8ff11fb0bd01f699e6db65; version=6a6dcae8f486c3f3298d0767d34505121c7b0b81 <df831e97739405ecbaddb85516bc7d4d1c933d6b

Published CVSS scores

5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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

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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