CVE-2026-31671

Kernel data disclosure via uncleared report padding

Published Apr 24, 2026 · Updated Apr 24, 2026

Information disclosure in Linux Kernel allows local users to read three uninitialized kernel padding bytes through XFRM reports. In xfrm_user build_report(), the kernel sets individual xfrm_user_report members without first clearing the structure, then copies its three alignment-padding bytes to userspace. Exploitation requires local low-privileged access and the ability to request an XFRM report; the disclosed data is limited to three bytes per response.

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

Information disclosure in Linux Kernel allows local users to read three uninitialized kernel padding bytes through XFRM reports. In xfrm_user build_report(), the kernel sets individual xfrm_user_report members without first clearing the structure, then copies its three alignment-padding bytes to userspace. Exploitation requires local low-privileged access and the ability to request an XFRM report; the disclosed data is limited to three bytes per response.

The record

CVE
CVE-2026-31671
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-401, T1005
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 <0616314b3b34f24cbb91da8c6bd8bcdc4c8592f9
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0a30dceb0e1f0c480d2482e6d7cebf8aebb6eb72
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6c55714c931051cd7f4839c19ce0867179fd22fe
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <716c546e88cfe49d841658240e10cb57bc50a2cc
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d10119968d0e1f2b669604baf2a8b5fdb72fa6b4
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d27c02eec529f78055a46a5c9e6c62684382b2d8
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e0c8542c3d097ed4205ded51868195d5d6ddac62
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ff5ee507302303b15859753c3e0d67d38fd12c88

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0616314b3b34f24cbb91da8c6bd8bcdc4c8592f9; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0a30dceb0e1f0c480d2482e6d7cebf8aebb6eb72; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6c55714c931051cd7f4839c19ce0867179fd22fe; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <716c546e88cfe49d841658240e10cb57bc50a2cc; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d10119968d0e1f2b669604baf2a8b5fdb72fa6b4; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d27c02eec529f78055a46a5c9e6c62684382b2d8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e0c8542c3d097ed4205ded51868195d5d6ddac62; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ff5ee507302303b15859753c3e0d67d38fd12c88

Published CVSS scores

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

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

CWE-401Missing Release of Memory after Effective Lifetime
T1005Data from Local System

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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