{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "e36ba5ab808ef6237c3148d469c8238674230e2b"
            },
            {
              "fixed": "04a177f91160ee18da98f5689482cf0f589ec869"
            },
            {
              "fixed": "0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72"
            },
            {
              "fixed": "be93d186ae88a92e7aa77e122d4e661fa57b1e39"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.15.0"
            },
            {
              "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-2026-64293.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\niommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read\n\nThe bound-check in iommufd_veventq_fops_read() for the normal vEVENT\npath uses sizeof(hdr) where the surrounding code uses sizeof(*hdr):\n\n\tif (!vevent_for_lost_events_header(cur) \u0026\u0026\n\t    sizeof(hdr) + cur-\u003edata_len \u003e count - done) {\n\nhdr is declared as struct iommufd_vevent_header *, so sizeof(hdr)\nevaluates to the size of the pointer.  Surrounding code uses\nsizeof(*hdr) consistently:\n\n\tif (done \u003e= count || sizeof(*hdr) \u003e count - done) {\n\t...\n\tif (copy_to_user(buf + done, hdr, sizeof(*hdr))) {\n\t...\n\tdone += sizeof(*hdr);\n\nstruct iommufd_vevent_header is currently 8 bytes (two __u32 fields,\nflags and sequence), so on 64-bit (sizeof(void *) == 8) the two\nexpressions happen to be equal and the check works as intended.\n\nOn 32-bit (sizeof(void *) == 4) the check under-counts the header by\n4 bytes: a vEVENT whose data_len causes 8 + cur-\u003edata_len to exceed\ncount - done while 4 + cur-\u003edata_len does not will pass the check,\nthen the loop will copy_to_user 8 bytes of header followed by data_len\nbytes of payload, writing past the user-supplied buffer.\n\nIt is also a latent bug for any future expansion of struct\niommufd_vevent_header beyond sizeof(void *) on 64-bit; the check\nshould not depend on the type happening to match the host pointer\nwidth.\n\nUse sizeof(*hdr) to match the rest of the function and the actual\namount that will be copied.",
  "id": "CVE-2026-64293",
  "modified": "2026-07-28T03:56:01.023507497Z",
  "published": "2026-07-25T08:49:31.945Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/04a177f91160ee18da98f5689482cf0f589ec869"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/be93d186ae88a92e7aa77e122d4e661fa57b1e39"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64293.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64293"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read"
}