CVE-2025-38733
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-09-05

Last updated on: 2025-11-25

Assigner: kernel.org

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.
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Meta Information
Published
2025-09-05
Last Modified
2025-11-25
Generated
2026-05-07
AI Q&A
2025-09-05
EPSS Evaluated
2026-05-05
NVD
CVE-2025-38733
Affected Vendors & Products
Showing 9 associated CPEs
Vendor Product Version / Range
linux linux_kernel 6.11
linux linux_kernel 6.11
linux linux_kernel 6.11
linux linux_kernel 6.11
linux linux_kernel 6.17
linux linux_kernel 6.17
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-476 The product dereferences a pointer that it expects to be valid but is NULL.
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability in the Linux kernel involves the s390 architecture's memory management where the lowcore region is incorrectly mapped with identity mapping at address zero. Because identity mapping is pinned to address zero, the lowcore is always mapped there, and if the relocate_lowcore option is used, the lowcore ends up being mapped twice. This causes NULL pointer accesses to succeed instead of causing exceptions, potentially allowing unintended memory access.


How can this vulnerability impact me? :

The vulnerability allows NULL pointer dereferences to succeed rather than causing exceptions, which can lead to unintended memory access or corruption. This could be exploited to bypass certain protections or cause system instability on affected Linux systems using the s390 architecture.


What immediate steps should I take to mitigate this vulnerability?

Update the Linux kernel to a version where this vulnerability is fixed, as the issue is resolved by not mapping the first two pages of physical memory with identity mapping. There are no specific configuration changes or commands provided to mitigate this vulnerability other than applying the kernel update.


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