CVE-2026-64559

Memory disclosure and corruption via unchecked ioctl length

Published Jul 29, 2026 · Updated Jul 29, 2026

Out-of-bounds access in affected Linux Kernel releases starting at 6.12 allows local users to read or corrupt kernel memory via /dev/pkey. PKEY_VERIFYPROTK multiplies the user-controlled protkey.len in 32-bit arithmetic for validation but passes the unchecked length to memcpy. The world-writable s390 device permits unprivileged local access without user interaction, causing kernel-stack disclosure, heap corruption, or a repeatable panic.

CVSS severity7.8
High
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

Out-of-bounds access in affected Linux Kernel releases starting at 6.12 allows local users to read or corrupt kernel memory via /dev/pkey. PKEY_VERIFYPROTK multiplies the user-controlled protkey.len in 32-bit arithmetic for validation but passes the unchecked length to memcpy. The world-writable s390 device permits unprivileged local access without user interaction, causing kernel-stack disclosure, heap corruption, or a repeatable panic.

The record

CVE
CVE-2026-64559
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-805, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 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=6.12
  2. Affected versionversion=8fcc231ce3bea12b78bb94b280cdc03cff342435 <0a9e34ccbe772b8f321388cdbdf4f22b94e513e7
  3. Affected versionversion=8fcc231ce3bea12b78bb94b280cdc03cff342435 <693bf91d4db134f9b1c2840c8e287eee3d993bac
  4. Affected versionversion=8fcc231ce3bea12b78bb94b280cdc03cff342435 <7e7e03848c918aa0acad5ffd75d929e3afec1554
  5. Affected versionversion=8fcc231ce3bea12b78bb94b280cdc03cff342435 <b3d4ab2d7df9426f7f1d3671d7e2108f2ca6e970

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.12; version=8fcc231ce3bea12b78bb94b280cdc03cff342435 <0a9e34ccbe772b8f321388cdbdf4f22b94e513e7; version=8fcc231ce3bea12b78bb94b280cdc03cff342435 <693bf91d4db134f9b1c2840c8e287eee3d993bac; version=8fcc231ce3bea12b78bb94b280cdc03cff342435 <7e7e03848c918aa0acad5ffd75d929e3afec1554; version=8fcc231ce3bea12b78bb94b280cdc03cff342435 <b3d4ab2d7df9426f7f1d3671d7e2108f2ca6e970

Published CVSS scores

7.8kernel.orgCVSS: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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-805Buffer Access with Incorrect Length Value
T1068Exploitation for Privilege Escalation

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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