{"api_version":"1","generated_at":"2026-08-08T12:56:47+00:00","cve":"CVE-2026-64293","urls":{"html":"https://cve.report/CVE-2026-64293","api":"https://cve.report/api/cve/CVE-2026-64293.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64293","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64293"},"summary":{"title":"iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read","description":"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) &&\n\t    sizeof(hdr) + cur->data_len > 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 >= count || sizeof(*hdr) > 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->data_len to exceed\ncount - done while 4 + cur->data_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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-25 10:17:10","updated_at":"2026-07-30 15:00:27"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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"}}],"references":[{"url":"https://git.kernel.org/stable/c/0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72","name":"https://git.kernel.org/stable/c/0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/04a177f91160ee18da98f5689482cf0f589ec869","name":"https://git.kernel.org/stable/c/04a177f91160ee18da98f5689482cf0f589ec869","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/be93d186ae88a92e7aa77e122d4e661fa57b1e39","name":"https://git.kernel.org/stable/c/be93d186ae88a92e7aa77e122d4e661fa57b1e39","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64293","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64293","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e36ba5ab808ef6237c3148d469c8238674230e2b 04a177f91160ee18da98f5689482cf0f589ec869 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e36ba5ab808ef6237c3148d469c8238674230e2b 0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e36ba5ab808ef6237c3148d469c8238674230e2b be93d186ae88a92e7aa77e122d4e661fa57b1e39 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.15 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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) &&\n\t    sizeof(hdr) + cur->data_len > 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 >= count || sizeof(*hdr) > 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->data_len to exceed\ncount - done while 4 + cur->data_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"}}],"providerMetadata":{"dateUpdated":"2026-07-27T04:59:30.042Z","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":"2026-07-27T04:59:30.042Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-25 10:17:10","lastModifiedDate":"2026-07-30 15:00:27","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64293","Ordinal":"1","Title":"iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read","CVE":"CVE-2026-64293","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64293","Ordinal":"1","NoteData":"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) &&\n\t    sizeof(hdr) + cur->data_len > 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 >= count || sizeof(*hdr) > 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->data_len to exceed\ncount - done while 4 + cur->data_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.","Type":"Description","Title":"iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read"}]}}}