CVE-2026-31699

Kernel-memory disclosure via failed PEK CSR copy

Published May 1, 2026 · Updated May 1, 2026

An out-of-bounds read in the SEV driver in Linux Kernel allows local users to disclose kernel memory through the PEK CSR ioctl. In sev_ioctl_do_pek_csr, a firmware failure caused by a short userspace buffer leaves the kernel allocation smaller than the firmware-required length, but copy_to_user still copies that larger length. A low-privilege local user with access to the SEV device can expose adjacent slab data and trigger a kernel memory fault, affecting confidentiality and availability without enabling data modification.

CVSS severity7.1
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An out-of-bounds read in the SEV driver in Linux Kernel allows local users to disclose kernel memory through the PEK CSR ioctl. In sev_ioctl_do_pek_csr, a firmware failure caused by a short userspace buffer leaves the kernel allocation smaller than the firmware-required length, but copy_to_user still copies that larger length. A low-privilege local user with access to the SEV device can expose adjacent slab data and trigger a kernel memory fault, affecting confidentiality and availability without enabling data modification.

The record

CVE
CVE-2026-31699
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-787, T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 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=4.16
  2. Affected versionversion=e799035609e1526761aa2f896a974b233d04d36d <111dcc6d0f016076745824a787d25609d0022f4c
  3. Affected versionversion=e799035609e1526761aa2f896a974b233d04d36d <3b4fd8f15765d9a3105b834dba8a05d025e5e16e
  4. Affected versionversion=e799035609e1526761aa2f896a974b233d04d36d <59e9ae81f8670ccc780bc75f45a355736f640ec9
  5. Affected versionversion=e799035609e1526761aa2f896a974b233d04d36d <607ba280f2adb5092cf5386c3935afac2ca0031a
  6. Affected versionversion=e799035609e1526761aa2f896a974b233d04d36d <abe4a6d6f606113251868c2c4a06ba904bb41eed

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4.16; version=e799035609e1526761aa2f896a974b233d04d36d <111dcc6d0f016076745824a787d25609d0022f4c; version=e799035609e1526761aa2f896a974b233d04d36d <3b4fd8f15765d9a3105b834dba8a05d025e5e16e; version=e799035609e1526761aa2f896a974b233d04d36d <59e9ae81f8670ccc780bc75f45a355736f640ec9; version=e799035609e1526761aa2f896a974b233d04d36d <607ba280f2adb5092cf5386c3935afac2ca0031a; version=e799035609e1526761aa2f896a974b233d04d36d <abe4a6d6f606113251868c2c4a06ba904bb41eed

Published CVSS scores

7.1kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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-787Out-of-bounds Write
T1005Data from Local System

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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