CVE-2025-21866

Kernel memory corruption via misclassified text mapping

Published Mar 12, 2025 · Updated May 11, 2026

Out-of-bounds write in Linux kernel 4.13 through 6.14-rc3 allows local users to corrupt kernel memory through PowerPC text patching. text_area_cpu_up marks a directly mapped virtual area as VM_ALLOC, so KASAN leaves it poisoned because __vmalloc_node_range never initializes it before copy_to_kernel_nofault writes. The observed failure requires a KASAN-enabled PowerPC kernel and a path that compiles a seccomp BPF program, with impact limited to kernel availability.

CVSS severity5.5
Medium
EPSS probability0.23%
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 write in Linux kernel 4.13 through 6.14-rc3 allows local users to corrupt kernel memory through PowerPC text patching. text_area_cpu_up marks a directly mapped virtual area as VM_ALLOC, so KASAN leaves it poisoned because __vmalloc_node_range never initializes it before copy_to_kernel_nofault writes. The observed failure requires a KASAN-enabled PowerPC kernel and a path that compiles a seccomp BPF program, with impact limited to kernel availability.

The record

CVE
CVE-2025-21866
Published
Mar 12, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-770, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 12, 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=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <2d542f13d26344e3452eee77613026ce9b653065
  2. Affected versionversion=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <2e6c80423f201405fd65254e52decd21663896f3
  3. Affected versionversion=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <6847b3e40bb963e57b61d1cc6fe84cb37b9d3d4c
  4. Affected versionversion=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <8d06e9208184b2851fa79a3a39d6860320c8bdf8
  5. Affected versionversion=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <97de5852058a299ba447cd9782fe96488d30108b
  6. Affected versionversion=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <c905a3053518212a1017e50bd2be3bee59305bb0
  7. Affected versionversion=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <d262a192d38e527faa5984629aabda2e0d1c4f54
  8. Affected versionversion=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <f8d4c5b653c1bc0df56e15658bbf64fc359adc4e
  9. Affected versionversion=4.13

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <2d542f13d26344e3452eee77613026ce9b653065; version=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <2e6c80423f201405fd65254e52decd21663896f3; version=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <6847b3e40bb963e57b61d1cc6fe84cb37b9d3d4c; version=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <8d06e9208184b2851fa79a3a39d6860320c8bdf8; version=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <97de5852058a299ba447cd9782fe96488d30108b; version=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <c905a3053518212a1017e50bd2be3bee59305bb0; version=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <d262a192d38e527faa5984629aabda2e0d1c4f54; version=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1 <f8d4c5b653c1bc0df56e15658bbf64fc359adc4e; version=4.13

Published CVSS scores

5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS: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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
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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