{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "bbf535fd6f06b94b9d07ed6f09397a936d4a58d8"
            },
            {
              "fixed": "ebb45c2648b1f60715fd283700f651e05e431231"
            },
            {
              "fixed": "09d2407985b8ce3e831f9d4310fe7ac06a6b3ae9"
            },
            {
              "fixed": "36f8534f461222291a74156ab91f3ba9f09b6f93"
            },
            {
              "fixed": "006467ab932698612398f853344a7405164541f4"
            },
            {
              "fixed": "b9beed2322f3538b0d2d53307062da4102b8d8d8"
            },
            {
              "fixed": "e30453c61e185e914fde83c650e268067b140218"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.0.0"
            },
            {
              "fixed": "6.1.178"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.145"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.96"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.39"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64417.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: shrinker: fix NULL pointer dereference in debugfs\n\nshrinker_debugfs_add() creates both \"count\" and \"scan\" debugfs files\nunconditionally.\n\nThat assumes every shrinker implements both count_objects() and\nscan_objects(), which is not guaranteed.  For example, the xen-backend\nshrinker sets count_objects() but leaves scan_objects() NULL, so writing\nto its scan file calls through a NULL function pointer and panics the\nkernel:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nRIP: 0010:0x0\nCode: Unable to access opcode bytes at 0xffffffffffffffd6.\nCall Trace:\n \u003cTASK\u003e\n shrinker_debugfs_scan_write+0x12e/0x270\n full_proxy_write+0x5f/0x90\n vfs_write+0xde/0x420\n ? filp_flush+0x75/0x90\n ? filp_close+0x1d/0x30\n ? do_dup2+0xb8/0x120\n ksys_write+0x68/0xf0\n ? filp_flush+0x75/0x90\n do_syscall_64+0xb3/0x5b0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThe count path has the same issue in principle if a shrinker omits\ncount_objects().\n\nTo fix it, only create \"count\" and \"scan\" debugfs files when the\ncorresponding callbacks are present.",
  "id": "CVE-2026-64417",
  "modified": "2026-07-27T03:56:24.633771793Z",
  "published": "2026-07-25T08:50:56.800Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/006467ab932698612398f853344a7405164541f4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/09d2407985b8ce3e831f9d4310fe7ac06a6b3ae9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/36f8534f461222291a74156ab91f3ba9f09b6f93"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b9beed2322f3538b0d2d53307062da4102b8d8d8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e30453c61e185e914fde83c650e268067b140218"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ebb45c2648b1f60715fd283700f651e05e431231"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64417.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64417"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "summary": "mm: shrinker: fix NULL pointer dereference in debugfs"
}