CVE-2025-21696 Affecting kernel-uki-virt package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

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  • Snyk IDSNYK-RHEL9-KERNELUKIVIRT-8729143
  • published15 Feb 2025
  • disclosed12 Feb 2025

Introduced: 12 Feb 2025

NewCVE-2025-21696  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-uki-virt.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-uki-virt package and not the kernel-uki-virt package as distributed by RHEL. See How to fix? for RHEL: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 Scores

version 3.1