CVE-2026-31575

Local crash via hugetlb mutex hash mismatch

Published Apr 24, 2026 · Updated Apr 24, 2026

Race condition in Linux Kernel allows local users to crash the system through concurrent userfaultfd operations on the same huge page. mfill_atomic_hugetlb passes a PAGE_SIZE-granularity index to hugetlb_fault_mutex_hash, so addresses in one huge page can select different mutexes. Low-privilege local access is required; competing faults can corrupt the reservation map and trigger the resv_map_release BUG_ON.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Linux Kernel allows local users to crash the system through concurrent userfaultfd operations on the same huge page. mfill_atomic_hugetlb passes a PAGE_SIZE-granularity index to hugetlb_fault_mutex_hash, so addresses in one huge page can select different mutexes. Low-privilege local access is required; competing faults can corrupt the reservation map and trigger the resv_map_release BUG_ON.

The record

CVE
CVE-2026-31575
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 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 <08282b1bf74c69fc8ecd25493e7fdb5460f01290
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <574501ede47ac439afd67ba9812bc66722d500ba
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f4689fc089765d36c026063fb22d23533e883eb6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <08282b1bf74c69fc8ecd25493e7fdb5460f01290; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <574501ede47ac439afd67ba9812bc66722d500ba; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f4689fc089765d36c026063fb22d23533e883eb6

Published CVSS scores

5.5CanonicalCVSS: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

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 exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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