CVE-2026-64514 Affecting kernel-rt package, versions *


Severity

Recommended
low

Based on CentOS security rating.

Threat Intelligence

EPSS
0.18% (8th percentile)

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  • Snyk IDSNYK-CENTOS10-KERNELRT-18403201
  • published30 Jul 2026
  • disclosed25 Jul 2026

Introduced: 25 Jul 2026

NewCVE-2026-64514  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-rt.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt package and not the kernel-rt package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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

userfaultfd: gate must_wait writability check on pte_present()

userfaultfd_must_wait() and userfaultfd_huge_must_wait() read the PTE without taking the page table lock and then apply pte_write() / huge_pte_write() to it. Those accessors decode bits from the present encoding only; on a swap or migration entry they read the offset bits that happen to share the same position and return an undefined result.

The intent of the check is "is this fault still WP-blocked?". A non-marker swap entry means the page is in transit -- the userfault context the original fault delivered against is no longer the same, and the swap-in or migration completion path will re-deliver a fresh fault if userspace still needs to handle it. Worst case under the current code the garbage write bit says "wait", and the thread stays asleep until a UFFDIO_WAKE that may never arrive.

Gate the writability check on pte_present() so the lockless re-check only inspects present-PTE bits when the entry is actually present. The non-present, non-marker case returns "don't wait" and lets the fault path retry.

CVSS Base Scores

version 3.1