{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.1.4-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  mm: page_ext: add count limit to page_ext_iter_next to prevent invalid PFN access  The page_ext iteration API does not validate if the PFN still belongs to a valid section while advancing the iterator.  When dynamically adding memory in the hotplug path, it can lead to a NULL pointer dereference during page_ext_lookup at the boundary of the last valid section when iterator count equals __pgcount.  The for_each_page_ext() macro calls page_ext_iter_next() as its loop increment.  for_each_page_ext() does a \"__page_ext = page_ext_iter_next(\u0026__iter)\" at the end.  This causes page_ext_iter_next() to increment iter-\u003eindex past __pgcount and call page_ext_lookup(start_pfn + __pgcount).  During memory hotplug (online), the PFN at start_pfn + __pgcount may belong to a section that has not yet been initialized, causing page_ext_lookup() to trigger a NULL pointer dereference.  [   14.555124][  T846] Call trace: [   14.555125][  T846]  lookup_page_ext+0x6c/0x108 (P) [   14.555127][  T846]  page_ext_lookup+0x30/0x3c [   14.555129][  T846]  __reset_page_owner+0x11c/0x260 [   14.571201][  T846]  __free_pages_ok+0x5e8/0x8e0 [   14.571204][  T846]  __free_pages_core+0x78/0xf0 [   14.571206][  T846]  generic_online_page+0x14/0x24 [   14.597782][  T846]  online_pages+0x178/0x30c [   14.597784][  T846]  memory_block_change_state+0x284/0x32c [   14.597787][  T846]  memory_subsys_online+0x4c/0x64 [   14.597789][  T846]  device_online+0x88/0xb0 [   14.597791][  T846]  online_memory_block+0x30/0x40 [   14.597793][  T846]  walk_memory_blocks+0xac/0xe8 [   14.597794][  T846]  add_memory_resource+0x280/0x298 [   14.656161][  T846]  add_memory+0x60/0x98  Move the iteration boundary enforcement inside the iterator functions, so callers cannot inadvertently access beyond the requested range.",
  "id": "DEBIAN-CVE-2026-64295",
  "modified": "2026-09-14T16:47:44.947630052Z",
  "published": "2026-07-25T10:17:10.277Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-64295"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-64295"
  ]
}