{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "54007f818206dc27309ca423df4c87dd160a7208"
            },
            {
              "fixed": "165613191ad9d034bf17c00e3a142f9561597ec5"
            },
            {
              "fixed": "0c26202b157f1efc3cd2f26f5c30f59b508a6a5d"
            },
            {
              "fixed": "3c58f641e813c3c71039f8fd4d4e2a3aab713288"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.6.0"
            },
            {
              "fixed": "6.18.44"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.1.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68166.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: prevent registration of special VMAs\n\nVova Tokarev says:\n\n  userfaultfd allows registration on shadow stack VMAs.  With userfaultfd\n  access, you can register on the shadow stack, discard a page ... and\n  inject a page with chosen return addresses via UFFDIO_COPY.\n\nUpdate vma_can_userfault() to reject VM_SHADOW_STACK.\n\nWhile on it, also reject VM_SPECIAL so that if a driver would implement\nvm_uffd_ops, it wouldn't be possible to register special VMAs with\nuserfaultfd.\n\nSince VM_SPECIAL includes VM_DONTEXPAND which is set but hugetlb, exclude\nhugetlb VMAs from the check for VM_SPECIAL.",
  "id": "CVE-2026-68166",
  "modified": "2026-08-12T03:51:31.359971915Z",
  "published": "2026-08-10T11:59:34.576Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0c26202b157f1efc3cd2f26f5c30f59b508a6a5d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/165613191ad9d034bf17c00e3a142f9561597ec5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3c58f641e813c3c71039f8fd4d4e2a3aab713288"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68166.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68166"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "userfaultfd: prevent registration of special VMAs"
}