--- id: CVE-2026-64368 title: |- In the Linux kernel, the following vulnerability has been resolved: mm/slab: do not limit zeroing to orig_size when only red zoning is enabled When init (zeroing) on allocation is requested, for kmalloc() we generally have to zero the … summary: |- In the Linux kernel, the following vulnerability has been resolved: mm/slab: do not limit zeroing to orig_size when only red zoning is enabled When init (zeroing) on allocation is requested, for kmalloc() we generally have to zero the … severity: high cvss: 8.1 cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H' published: '2026-07-25' updated: '2026-07-27' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64368' references: - url: 'https://git.kernel.org/stable/c/0d18ccef142f04433dfb2a0c120cf223d2b8a42c' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/2382971aaaef5bf85a651234c64906f59580b8be' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/6256899c3a34674bba6076884aedbba49fc695e4' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/648927ceb84021a25a0fbd5673740956f318d534' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/7e706d50fa119eead6376bf0ef973e8d73a96030' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64368.json - url: 'https://access.redhat.com/security/cve/CVE-2026-64368' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2507213' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-64368' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64368' - url: >- https://lore.kernel.org/linux-cve-announce/2026072522-CVE-2026-64368-014f@gregkh/T - url: 'https://access.redhat.com/errata/RHSA-2026:53330' - url: 'https://access.redhat.com/errata/RHSA-2026:69908' - url: 'https://access.redhat.com/errata/RHSA-2026:70484' - url: 'https://access.redhat.com/errata/RHSA-2026:53329' tags: - nvd - csaf - vex - red-hat - score-dispute epss: 0.00417 epssPercentile: 0.33249 ingestedAt: '2026-07-27T06:16:50.810Z' vendor: Red Hat product: Red Hat Enterprise Linux BaseOS E4S (v.9.4) affected: - enterprise_linux 9 - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_e4s_v_9_4 - enterprise_linux_appstream_eus_v_9_6 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_e4s_v_9_4 - enterprise_linux_baseos_eus_v_9_6 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_v_10 - codeready_linux_builder_eus_v_9_6 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_real_time_for_nfv_e4s_v_9_4 - enterprise_linux_real_time_for_nfv_eus_v_9_6 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_v_10 - enterprise_linux_real_time_e4s_v_9_4 - enterprise_linux_real_time_eus_v_9_6 - enterprise_linux_real_time_v_9 patched: - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_e4s_v_9_4 - enterprise_linux_appstream_eus_v_9_6 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_e4s_v_9_4 - enterprise_linux_baseos_eus_v_9_6 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_v_10 - codeready_linux_builder_eus_v_9_6 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_real_time_for_nfv_e4s_v_9_4 - enterprise_linux_real_time_for_nfv_eus_v_9_6 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_v_10 - enterprise_linux_real_time_e4s_v_9_4 - enterprise_linux_real_time_eus_v_9_6 - enterprise_linux_real_time_v_9 cwe: - CWE-824 scores: nvd: 8.1 vendor: 5.5 --- ## Overview In the Linux kernel, the following vulnerability has been resolved: mm/slab: do not limit zeroing to orig_size when only red zoning is enabled When init (zeroing) on allocation is requested, for kmalloc() we generally have to zero the full object size even if a smaller size is requested, in order to provide krealloc()'s __GFP_ZERO guarantees. But if we track the requested size, krealloc() uses that information to do the right thing, so we can zero only the requested size. With red zoning also enabled, any extra size became part of the red zone, so it must not be zeroed and thus we must zero only the requested size. However the current check is imprecise, and will trigger also when only SLAB_RED_ZONE is enabled without SLAB_STORE_USER (which enables tracking the requested size). This means enabling red zoning alone can compromise krealloc()'s __GFP_ZERO contract. Fix this by using slub_debug_orig_size() instead, which is the exact check for whether the requested size is tracked. We don't need to care if red zoning is also enabled or not. Also update and expand the comment accordingly. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **RHSA-2026:53330** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10), Red Hat Enterprise Linux Real Time (v. 10) · released 2026-08-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:53330) - **RHSA-2026:69908** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4), Red Hat Enterprise Linux BaseOS E4S (v.9.4), Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4), Red Hat Enterprise Linux Real Time E4S (v.9.4) · released 2026-09-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:69908) - **RHSA-2026:70484** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat Enterprise Linux BaseOS EUS (v.9.6), Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6), Red Hat Enterprise Linux Real Time EUS (v.9.6) · released 2026-09-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:70484) - **RHSA-2026:53329** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Real Time for NFV (v. 9), Red Hat Enterprise Linux Real Time (v. 9) · released 2026-08-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:53329) - **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 9 · updated 2026-09-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64368.json)