CVE-2026-64293 (GCVE-0-2026-64293)
Vulnerability from cvelistv5
Published
2026-07-25 08:49
Modified
2026-10-19 20:38
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read The bound-check in iommufd_veventq_fops_read() for the normal vEVENT path uses sizeof(hdr) where the surrounding code uses sizeof(*hdr): if (!vevent_for_lost_events_header(cur) && sizeof(hdr) + cur->data_len > count - done) { hdr is declared as struct iommufd_vevent_header *, so sizeof(hdr) evaluates to the size of the pointer. Surrounding code uses sizeof(*hdr) consistently: if (done >= count || sizeof(*hdr) > count - done) { ... if (copy_to_user(buf + done, hdr, sizeof(*hdr))) { ... done += sizeof(*hdr); struct iommufd_vevent_header is currently 8 bytes (two __u32 fields, flags and sequence), so on 64-bit (sizeof(void *) == 8) the two expressions happen to be equal and the check works as intended. On 32-bit (sizeof(void *) == 4) the check under-counts the header by 4 bytes: a vEVENT whose data_len causes 8 + cur->data_len to exceed count - done while 4 + cur->data_len does not will pass the check, then the loop will copy_to_user 8 bytes of header followed by data_len bytes of payload, writing past the user-supplied buffer. It is also a latent bug for any future expansion of struct iommufd_vevent_header beyond sizeof(void *) on 64-bit; the check should not depend on the type happening to match the host pointer width. Use sizeof(*hdr) to match the rest of the function and the actual amount that will be copied.
References
Impacted products
Vendor Product Version
Linux Linux Version: e36ba5ab808ef6237c3148d469c8238674230e2b
Version: e36ba5ab808ef6237c3148d469c8238674230e2b
Version: e36ba5ab808ef6237c3148d469c8238674230e2b
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-64293",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T15:38:30.670764Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-787",
                "description": "CWE-787 Out-of-bounds Write",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-19T20:38:22.244Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/iommufd/eventq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "04a177f91160ee18da98f5689482cf0f589ec869",
              "status": "affected",
              "version": "e36ba5ab808ef6237c3148d469c8238674230e2b",
              "versionType": "git"
            },
            {
              "lessThan": "0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72",
              "status": "affected",
              "version": "e36ba5ab808ef6237c3148d469c8238674230e2b",
              "versionType": "git"
            },
            {
              "lessThan": "be93d186ae88a92e7aa77e122d4e661fa57b1e39",
              "status": "affected",
              "version": "e36ba5ab808ef6237c3148d469c8238674230e2b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/iommufd/eventq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.39",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.4",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable function is reached through read() on a locally held iommufd vEVENTQ file descriptor; it is not directly network- or device-packet-facing.\nAC:L - On an affected 32-bit deployment, the attacker can deterministically queue an event and choose a count that is one to four bytes too small; no race or uncontrollable condition is required.\nPR:L - No capability check occurs during the vulnerable read, and an unprivileged VMM or user granted an iommufd/vEVENTQ descriptor can invoke it without real init-namespace root.\nUI:N - Exploitation requires only attacker-controlled event generation and a read syscall; no separate victim action is required.\nS:U - The corruption occurs through the host kernel\u0027s userspace API and does not itself bypass an IOMMU boundary or demonstrate a guest-to-host escape.\nC:H - The four-byte overwrite can replace a complete pointer or control word in a 32-bit event consumer, potentially enabling code execution and disclosure of arbitrary process secrets.\nI:H - The kernel writes up to four payload bytes beyond the declared userspace buffer, which can corrupt a full 32-bit control value and potentially permit control-flow hijacking.\nA:H - The overwrite can crash a privileged VMM or other event-consuming service, and controllable event generation permits the condition to be triggered repeatedly."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:52:50.497Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/04a177f91160ee18da98f5689482cf0f589ec869"
        },
        {
          "url": "https://git.kernel.org/stable/c/0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72"
        },
        {
          "url": "https://git.kernel.org/stable/c/be93d186ae88a92e7aa77e122d4e661fa57b1e39"
        }
      ],
      "title": "iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64293",
    "datePublished": "2026-07-25T08:49:31.945Z",
    "dateReserved": "2026-07-19T15:36:31.778Z",
    "dateUpdated": "2026-10-19T20:38:22.244Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-64293\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-10-16T15:38:30.670764Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-787\", \"description\": \"CWE-787 Out-of-bounds Write\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-10-16T15:38:31.659Z\"}}], \"cna\": {\"title\": \"iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 7.8, \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"AV:L - The vulnerable function is reached through read() on a locally held iommufd vEVENTQ file descriptor; it is not directly network- or device-packet-facing.\\nAC:L - On an affected 32-bit deployment, the attacker can deterministically queue an event and choose a count that is one to four bytes too small; no race or uncontrollable condition is required.\\nPR:L - No capability check occurs during the vulnerable read, and an unprivileged VMM or user granted an iommufd/vEVENTQ descriptor can invoke it without real init-namespace root.\\nUI:N - Exploitation requires only attacker-controlled event generation and a read syscall; no separate victim action is required.\\nS:U - The corruption occurs through the host kernel\u0027s userspace API and does not itself bypass an IOMMU boundary or demonstrate a guest-to-host escape.\\nC:H - The four-byte overwrite can replace a complete pointer or control word in a 32-bit event consumer, potentially enabling code execution and disclosure of arbitrary process secrets.\\nI:H - The kernel writes up to four payload bytes beyond the declared userspace buffer, which can corrupt a full 32-bit control value and potentially permit control-flow hijacking.\\nA:H - The overwrite can crash a privileged VMM or other event-consuming service, and controllable event generation permits the condition to be triggered repeatedly.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"e36ba5ab808ef6237c3148d469c8238674230e2b\", \"lessThan\": \"04a177f91160ee18da98f5689482cf0f589ec869\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"e36ba5ab808ef6237c3148d469c8238674230e2b\", \"lessThan\": \"0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"e36ba5ab808ef6237c3148d469c8238674230e2b\", \"lessThan\": \"be93d186ae88a92e7aa77e122d4e661fa57b1e39\", \"versionType\": \"git\"}], \"programFiles\": [\"drivers/iommu/iommufd/eventq.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"6.15\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"6.15\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"6.18.39\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.18.*\"}, {\"status\": \"unaffected\", \"version\": \"7.1.4\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"7.1.*\"}, {\"status\": \"unaffected\", \"version\": \"7.2\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"drivers/iommu/iommufd/eventq.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/04a177f91160ee18da98f5689482cf0f589ec869\"}, {\"url\": \"https://git.kernel.org/stable/c/0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72\"}, {\"url\": \"https://git.kernel.org/stable/c/be93d186ae88a92e7aa77e122d4e661fa57b1e39\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"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.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.39\", \"versionStartIncluding\": \"6.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.1.4\", \"versionStartIncluding\": \"6.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.2\", \"versionStartIncluding\": \"6.15\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-17T04:52:50.497Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-64293\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T20:38:22.244Z\", \"dateReserved\": \"2026-07-19T15:36:31.778Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-07-25T08:49:31.945Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.