CVE-2026-64181

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description An issue exists in the memory management system where vm normal page() fails to handle missing support for pmd special() and pud special(). On x86 32-bit systems with Transparent Huge Pages (THP) enabled, the zap huge pmd() function can trigger warnings and lead to bad RSS-counter and page states when shrink huge zero folio scan() is called during reclaim. This occurs because the PAGE SPECIAL bit is not set in the huge zero Page Middle Directory (PMD) on 32-bit architectures, as CONFIG ARCH SUPPORTS PMD PFNMAP is never enabled for them. This oversight can cause huge zero folios to be incorrectly accounted as file-backed THP in smaps, pagemap, and numamaps, and may cause folio walk start() to return a folio even when FW ZEROPAGE is not set. The issue is addressed by updating vm normal page pmd() and vm normal page pud() to verify if pmd special or pud special are implemented.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.