CVE-2025-38733: s390/mm: Do not map lowcore with identity mapping
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 relocatelowcore 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.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2025-38733?
CVE-2025-38733 has been classified with a severity level that warrants immediate attention due to its potential impact on system memory mapping.
How do I fix CVE-2025-38733?
To address CVE-2025-38733, ensure you update your Linux kernel to the patched version that resolves this vulnerability.
Who is affected by CVE-2025-38733?
CVE-2025-38733 affects systems running certain versions of the Linux kernel that utilize identity mapping for lowcore.
What are the potential impacts of CVE-2025-38733?
CVE-2025-38733 could lead to memory management issues, which may result in system instability or unauthorized access.
When was CVE-2025-38733 disclosed?
CVE-2025-38733 was disclosed in 2025 as part of ongoing security improvements to the Linux kernel.