# CVE-2026-64293: linux: In the Linux kernel, the following vulnerability has been resolved: iommufd: Use sizeof(*hdr) instead of sizeof(hdr)... CVE-2026-64293 is fixed in 20 products on 1 platform, first by ALAS2023-2026-2045, released August 3, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-64293 - Priority: High - CVSS: 7.8 (high) - EPSS: 0.0017 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Jul 25, 2026 ## Description 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. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.18 amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel-livepatch-6.18.39-79.141 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | linux Debian 14 | 7.1.4-1 | [DEBIAN-CVE-2026-64293](https://patchblox.com/security/data/fix/linux/debian-cve-2026-64293.md) | Aug 7, 2026 | | Linux | microvm-kernel6.18 amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.39-79.141.amzn2023 | [ALAS2023-2026-2045](https://patchblox.com/security/data/fix/linux/alas2023-2026-2045.md) | Aug 3, 2026 | --- Data as of 2026-11-08T00:53:09Z UTC. 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