CVE-2026-31787

Kernel lockdown bypass via privcmd double free

Published Apr 30, 2026 · Updated Apr 30, 2026

Double free in the Xen privcmd driver in Linux Kernel allows local administrators of PVH or HVM domains to bypass kernel lockdown. A partial munmap splits a privcmd VMA, and vm_area_dup copies its pages pointer without an open callback, leaving both VMAs to free the same allocation. Exploitation requires root in a secure-mode Linux domain and permits kernel actions that lockdown is intended to prohibit.

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

Double free in the Xen privcmd driver in Linux Kernel allows local administrators of PVH or HVM domains to bypass kernel lockdown. A partial munmap splits a privcmd VMA, and vm_area_dup copies its pages pointer without an open callback, leaving both VMAs to free the same allocation. Exploitation requires root in a secure-mode Linux domain and permits kernel actions that lockdown is intended to prohibit.

The record

CVE
CVE-2026-31787
Published
Apr 30, 2026
Updated
Apr 30, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-415, T1562.001
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Apr 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1576ff3869cbd3620717195f971c85b7d7fd62b5
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2894a351fe2ea8684919d36df3188b9a35e3926f
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2b985d3a024b9e8c24e21671b34e855569763808
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <402d84ad9e89bd4cbfd07ca8598532b7021daf95
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <446ee446d9ae66f36e95c3c90bbcc4e56b94cde0
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <71bf829800758a6e3889096e4754ef47ba7fc850
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dbf862ce9f009128ab86b234d91413a3e450beb4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1576ff3869cbd3620717195f971c85b7d7fd62b5; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2894a351fe2ea8684919d36df3188b9a35e3926f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2b985d3a024b9e8c24e21671b34e855569763808; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <402d84ad9e89bd4cbfd07ca8598532b7021daf95; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <446ee446d9ae66f36e95c3c90bbcc4e56b94cde0; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <71bf829800758a6e3889096e4754ef47ba7fc850; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dbf862ce9f009128ab86b234d91413a3e450beb4

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-415Double Free
T1562.001Impair Defenses: Disable or Modify Tools

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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