CVE-2026-64558

Local privilege escalation via unchecked protected-key length

Published Jul 29, 2026 · Updated Jul 29, 2026

Out-of-bounds write in the s390 pkey component of Linux Kernel allows local users to gain kernel privileges through crafted key ioctls. The pkey_pckmo key_to_protkey handler copies a generated 160-byte protected-key token into a caller-provided 64-byte buffer without first validating its length. An unprivileged local user can reach the path through /dev/pkey or AF_ALG, overwrite kernel stack control data, or panic the system.

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 write in the s390 pkey component of Linux Kernel allows local users to gain kernel privileges through crafted key ioctls. The pkey_pckmo key_to_protkey handler copies a generated 160-byte protected-key token into a caller-provided 64-byte buffer without first validating its length. An unprivileged local user can reach the path through /dev/pkey or AF_ALG, overwrite kernel stack control data, or panic the system.

The record

CVE
CVE-2026-64558
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
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 <02028a24e26d85262ab9c8fc4344e1f3503007fc
  3. Affected versionversion=8fcc231ce3bea12b78bb94b280cdc03cff342435 <1ac287e2af9a9112fe271427ef45eceb26bce8b4
  4. Affected versionversion=8fcc231ce3bea12b78bb94b280cdc03cff342435 <433e5e70cdc1edf382d28d08a885b22e2b98b7da
  5. Affected versionversion=8fcc231ce3bea12b78bb94b280cdc03cff342435 <614aa0491c7a190556c2345dddee0b6f5ed90989

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.12; version=8fcc231ce3bea12b78bb94b280cdc03cff342435 <02028a24e26d85262ab9c8fc4344e1f3503007fc; version=8fcc231ce3bea12b78bb94b280cdc03cff342435 <1ac287e2af9a9112fe271427ef45eceb26bce8b4; version=8fcc231ce3bea12b78bb94b280cdc03cff342435 <433e5e70cdc1edf382d28d08a885b22e2b98b7da; version=8fcc231ce3bea12b78bb94b280cdc03cff342435 <614aa0491c7a190556c2345dddee0b6f5ed90989

Published CVSS scores

7.8LinuxCVSS: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

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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