CVE-2025-21696 Affecting kernel-uek-debug package, versions <0:6.12.0-101.33.4.3.el9uek


Severity

Recommended
high

Based on Oracle Linux security rating.

Threat Intelligence

EPSS
0.03% (6th percentile)

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  • Snyk IDSNYK-ORACLE9-KERNELUEKDEBUG-10780219
  • published18 Jul 2025
  • disclosed12 Feb 2025

Introduced: 12 Feb 2025

CVE-2025-21696  (opens in a new tab)

How to fix?

Upgrade Oracle:9 kernel-uek-debug to version 0:6.12.0-101.33.4.3.el9uek or higher.
This issue was patched in ELSA-2025-20480.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-uek-debug package and not the kernel-uek-debug package as distributed by Oracle. See How to fix? for Oracle:9 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

mm: clear uffd-wp PTE/PMD state on mremap()

When mremap()ing a memory region previously registered with userfaultfd as write-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in flag clearing leads to a mismatch between the vma flags (which have uffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp cleared). This mismatch causes a subsequent mprotect(PROT_WRITE) to trigger a warning in page_table_check_pte_flags() due to setting the pte to writable while uffd-wp is still set.

Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any such mremap() so that the values are consistent with the existing clearing of VM_UFFD_WP. Be careful to clear the logical flag regardless of its physical form; a PTE bit, a swap PTE bit, or a PTE marker. Cover PTE, huge PMD and hugetlb paths.

CVSS Base Scores

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