io_uring/nop: fix file reference leak with IOSQE_FIXED_FILE

{
  "id": "a49ff9feeb5b8a32f737ba80bf911fc559f65550d5f73e6e42e66c28426476e7",
  "url": "https://osv.dev/vulnerability/CVE-2026-64426",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "io_uring/nop: fix file reference leak with IOSQE_FIXED_FILE",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: io_uring/nop: fix file reference leak with IOSQE_FIXED_FILE NOP file-acquisition support choses between a fixed (registered) file and a normal fget()'d file based on its own IORING_NOP_FIXED_FILE flag in sqe->nop_flags. However, a request's REQ_F_FIXED_FILE is set independently from the generic IOSQE_FIXED_FILE sqe flag during request init, before the issue handler runs. If a NOP is submitted with IOSQE_FIXED_FILE set (so REQ_F_FIXED_FILE is set) but without IORING_NOP_FIXED_FILE, io_nop() takes the normal path and grabs a real reference via io_file_get_normal(). On completion, io_put_file() only drops the reference when REQ_F_FIXED_FILE is clear, so the fget()'d file is never released and leaks: BUG: memory leak unreferenced object 0xffff88800f42c240 (size 176): kmem_cache_alloc_noprof+0x358/0x440 alloc_empty_file+0x57/0x180 path_openat+0x44/0x1e50 do_file_open+0x121/0x200 do_sys_openat2+0xa7/0x150 __x64_sys_openat+0x82/0xf0 Decide between fixed and normal file acquisition from REQ_F_FIXED_FILE, the same way io_assign_file() does for every other opcode, and fold IORING_NOP_FIXED_FILE into REQ_F_FIXED_FILE at prep time.",
    "evidence": "osv:CVE-2026-64426",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.39",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-64426",
      "aliases": [
        "CVE-2026-64426"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "a85f31052bce52111b4e9d5a536003481d0421d0"
                },
                {
                  "fixed": "722869fcff598fad20d5ab79c305897a7534708b"
                },
                {
                  "fixed": "7267717f35787167fcce4bc14f6ef3fa06682dcf"
                },
                {
                  "fixed": "2564ca2e31bd8ee8348362941af2ee4671e487ca"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64426.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.39"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64426.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:22.889037101Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2564ca2e31bd8ee8348362941af2ee4671e487ca",
        "https://git.kernel.org/stable/c/722869fcff598fad20d5ab79c305897a7534708b",
        "https://git.kernel.org/stable/c/7267717f35787167fcce4bc14f6ef3fa06682dcf",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64426.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64426",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64426.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64426",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 488932,
  "published_at": "2026-07-25T08:51:03.867+00:00"
}