{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.0.12-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()  On x86 32-bit with THP enabled, zap_huge_pmd() is seen to generate a \"WARNING: mm/memory.c:735 at __vm_normal_page+0x6a/0x7d\", from the VM_WARN_ON_ONCE(is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)); followed by \"BUG: Bad rss-counter state\"s, then later \"BUG: Bad page state\"s when reclaim gets to call shrink_huge_zero_folio_scan().  It's as if the _PAGE_SPECIAL bit never got set in the huge_zero pmd: and indeed, whereas pte_special() and pte_mkspecial() are subject to a dedicated CONFIG_ARCH_HAS_PTE_SPECIAL, pmd_special() and pmd_mkspecial() are subject to CONFIG_ARCH_SUPPORTS_PMD_PFNMAP, which is never enabled on any 32-bit architecture.  While the problem was exposed through commit d80a9cb1a64a (\"mm/huge_memory: add and use normal_or_softleaf_folio_pmd()\"), it was an oversight in commit af38538801c6 (\"mm/memory: factor out common code from vm_normal_page_*()\") and would result in other problems: * huge zero folio accounted in smaps, pagemap (PAGE_IS_FILE) and   numamaps as file-backed THP * folio_walk_start() returning the folio even without FW_ZEROPAGE set.   Callers seem to tolerate that, though.  ... and triggering the VM_WARN_ON_ONE(), although never reported so far.  To fix it, teach vm_normal_page_pmd()/vm_normal_page_pud() to consider whether pmd_special/pud_special is actually implemented.",
  "id": "DEBIAN-CVE-2026-64181",
  "modified": "2026-09-14T16:47:43.579814700Z",
  "published": "2026-07-19T16:18:00.493Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-64181"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-64181"
  ]
}