CVE-2025-21949

Local kernel crash via misaligned hugetlb mapping

Published Apr 1, 2025 · Updated Aug 5, 2026

Memory-management flaw in Linux 5.19 through 6.13.6 on LoongArch allows local users to crash the kernel during hugetlb teardown. The LoongArch mmap allocator can return a hugetlbfs base address that is not PMD-aligned, causing __unmap_hugepage_range to hit a kernel BUG when the mapping is removed. A local low-privileged process can trigger the fault through huge-page mappings; the reported consequence is a kernel oops and possible host panic.

CVSS severity7.8
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory-management flaw in Linux 5.19 through 6.13.6 on LoongArch allows local users to crash the kernel during hugetlb teardown. The LoongArch mmap allocator can return a hugetlbfs base address that is not PMD-aligned, causing __unmap_hugepage_range to hit a kernel BUG when the mapping is removed. A local low-privileged process can trigger the fault through huge-page mappings; the reported consequence is a kernel oops and possible host panic.

The record

CVE
CVE-2025-21949
Published
Apr 1, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 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=5.19
  2. Affected versionversion=fa96b57c149061f71a70bd6582d995f6424fbbf4 <242b34f48a377afe4b285b472bd0f17744fca8e8
  3. Affected versionversion=fa96b57c149061f71a70bd6582d995f6424fbbf4 <3109d5ff484b7bc7b955f166974c6776d91f247b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.19; version=fa96b57c149061f71a70bd6582d995f6424fbbf4 <242b34f48a377afe4b285b472bd0f17744fca8e8; version=fa96b57c149061f71a70bd6582d995f6424fbbf4 <3109d5ff484b7bc7b955f166974c6776d91f247b

Published CVSS scores

7.8LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.5CISACVSS: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

T1499.004Application or System Exploitation

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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