In the Linux kernel, the following vulnerability has been resolved: s390/mm: Do not map lowcore with identity mapping Since the identity mapping is pinned to address zero the lowcore is always also mapped to address zero, this happens regardless of the relocate_lowcore command line option. If the option is specified the lowcore is mapped twice, instead of only once. This means that NULL pointer accesses will succeed instead of causing an exception (low address protection still applies, but covers only parts). To fix this never map the first two pages of physical memory with the identity mapping.

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

Vendors Products
Linux
  • Linux Kernel

No data.

No data.

References
Link Providers
https://git.kernel.org/stable/c/1d7864acd497cb468a998d44631f84896f885e85 cve-icon cve-icon
https://git.kernel.org/stable/c/30bf5728bb217a6d1ba73f44094c9b9c6bc9a567 cve-icon cve-icon
https://git.kernel.org/stable/c/93f616ff870a1fb7e84d472cad0af651b18f9f87 cve-icon cve-icon
https://lore.kernel.org/linux-cve-announce/2025090543-CVE-2025-38733-65a1@gregkh/T cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2025-38733 cve-icon
https://www.cve.org/CVERecord?id=CVE-2025-38733 cve-icon
History

Sat, 06 Sep 2025 09:15:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel

Sat, 06 Sep 2025 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low

Fri, 05 Sep 2025 17:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: s390/mm: Do not map lowcore with identity mapping Since the identity mapping is pinned to address zero the lowcore is always also mapped to address zero, this happens regardless of the relocate_lowcore command line option. If the option is specified the lowcore is mapped twice, instead of only once. This means that NULL pointer accesses will succeed instead of causing an exception (low address protection still applies, but covers only parts). To fix this never map the first two pages of physical memory with the identity mapping.
Title s390/mm: Do not map lowcore with identity mapping
References
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2025-09-05T17:20:33.075Z

Updated: 2025-09-05T17:20:33.075Z

Reserved: 2025-04-16T04:51:24.033Z

Link: CVE-2025-38733

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-09-05T18:15:42.550

Modified: 2025-09-08T16:25:59.157

Link: CVE-2025-38733

cve-icon Redhat

Severity : Low

Publid Date: 2025-09-05T00:00:00Z

Links: CVE-2025-38733 - Bugzilla