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Fencer Vulns
high 8.1

CVE-2026-64368 json

mm/slab: do not limit zeroing to orig_size when only red zoning is enabled

published 2026-07-25 3 mo ago modified 2026-10-19 20 d ago also EUVD-2026-48912

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits
0
none known

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 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.

Patch / fix

  • Linux Linux 6.6.145, 6.12.96, 6.18.39, 7.1.4, 7.2
  • linux Debian 13 6.12.96-1
  • linux Debian 14 7.1.4-1
  • linux-6.12 Debian 12 6.12.100-1~deb12u1

debian advisories DEBIAN-CVE-2026-64368

  • linux Ubuntu 24.04 LTS 6.8.0-147.147
  • linux Ubuntu 26.04 LTS 7.0.0-31.31
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1012.12
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1011.11
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1066.74
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1006.7

ubuntu advisories UBUNTU-CVE-2026-64368

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-687.38.1.el9_8
  • rv RHEL 9 5.14.0-687.38.1.el9_8
  • perf RHEL 9 5.14.0-687.38.1.el9_8
  • rtla RHEL 9 5.14.0-687.38.1.el9_8
  • libperf RHEL 9 5.14.0-687.38.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.38.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.38.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.38.1.el9_8

red hat advisories RHSA-2026:75560RHSA-2026:70484RHSA-2026:69908RHSA-2026:53329RHSA-2026:53330

  • kernel-rt Linux Micro 6.2 6.12.0-160000.38.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1
  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.38.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1.160000.2.23
  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.38.1
  • kernel-azure SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.38.1
  • kernel-obs-qa SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.38.1

suse advisories SUSE-SU-2026:23887-1SUSE-SU-2026:23902-1SUSE-SU-2026:23897-1SUSE-SU-2026:23881-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.38.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.38.1

opensuse advisories openSUSE-SU-2026:21910-1openSUSE-SU-2026:11476-1

  • kernel AlmaLinux 9 5.14.0-687.38.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.38.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.38.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.38.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.38.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.38.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.38.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.38.1.el9_8

almalinux advisories ALSA-2026:53329ALSA-2026:53330

  • kernel Rocky Linux 10 6.12.0-211.46.1.el10_2
  • kernel Rocky Linux 9 5.14.0-687.38.1.el9_8

rocky linux advisories RLSA-2026:53330RLSA-2026:53329

  • kernel Azure Linux 3.0 6.6.145.2-1

azure linux advisories AZL-93467

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-64368 updated cvss 5.5

kernel: mm/slab: do not limit zeroing to orig_size when only red zoning is enabled

  • Red Hat CodeReady Linux Builder EUS (v.9.6) libperf 5.14.0-570.142.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-570.142.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-570.142.1.el9_6, kernel-debuginfo-common-aarch64 5.14.0-570.142.1.el9_6, kernel-debuginfo-common-ppc64le 5.14.0-570.142.1.el9_6
    fixed: vendor fix RHSA-2026:70484
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.38.1.el9_8, perf 5.14.0-687.38.1.el9_8, rtla 5.14.0-687.38.1.el9_8, python3-perf 5.14.0-687.38.1.el9_8, kernel-devel-matched 5.14.0-687.38.1.el9_8, kernel-64k-devel-matched 5.14.0-687.38.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.46.1.el10_2, perf 6.12.0-211.46.1.el10_2, rtla 6.12.0-211.46.1.el10_2, python3-perf 6.12.0-211.46.1.el10_2, kernel-devel-matched 6.12.0-211.46.1.el10_2, kernel-64k-devel-matched 6.12.0-211.46.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:53330
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) rv 5.14.0-427.151.1.el9_4, perf 5.14.0-427.151.1.el9_4, rtla 5.14.0-427.151.1.el9_4, kernel-devel-matched 5.14.0-427.151.1.el9_4, kernel-64k-devel-matched 5.14.0-427.151.1.el9_4, kernel-debug-devel-matched 5.14.0-427.151.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:69908
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.108.1.el10_0, perf 6.12.0-55.108.1.el10_0, rtla 6.12.0-55.108.1.el10_0, python3-perf 6.12.0-55.108.1.el10_0, kernel-devel-matched 6.12.0-55.108.1.el10_0, kernel-64k-devel-matched 6.12.0-55.108.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:75560
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) rv 5.14.0-570.142.1.el9_6, perf 5.14.0-570.142.1.el9_6, rtla 5.14.0-570.142.1.el9_6, python3-perf 5.14.0-570.142.1.el9_6, kernel-devel-matched 5.14.0-570.142.1.el9_6, kernel-64k-devel-matched 5.14.0-570.142.1.el9_6, +7 more
    fixed: vendor fix RHSA-2026:70484
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.38.1.el9_8, kernel-64k 5.14.0-687.38.1.el9_8, kernel-core 5.14.0-687.38.1.el9_8, kernel-tools 5.14.0-687.38.1.el9_8, kernel-modules 5.14.0-687.38.1.el9_8, kernel-64k-core 5.14.0-687.38.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.46.1.el10_2, kernel-64k 6.12.0-211.46.1.el10_2, kernel-core 6.12.0-211.46.1.el10_2, kernel-tools 6.12.0-211.46.1.el10_2, kernel-modules 6.12.0-211.46.1.el10_2, kernel-64k-core 6.12.0-211.46.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:53330
show 17 more
  • Red Hat Enterprise Linux BaseOS E4S (v.9.4) bpftool 7.3.0-427.151.1.el9_4, kernel 5.14.0-427.151.1.el9_4, kernel-64k 5.14.0-427.151.1.el9_4, kernel-core 5.14.0-427.151.1.el9_4, kernel-tools 5.14.0-427.151.1.el9_4, python3-perf 5.14.0-427.151.1.el9_4, +28 more
    fixed: vendor fix RHSA-2026:69908
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.108.1.el10_0, kernel-64k 6.12.0-55.108.1.el10_0, kernel-core 6.12.0-55.108.1.el10_0, kernel-tools 6.12.0-55.108.1.el10_0, kernel-modules 6.12.0-55.108.1.el10_0, kernel-64k-core 6.12.0-55.108.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:75560
  • Red Hat Enterprise Linux BaseOS EUS (v.9.6) kernel 5.14.0-570.142.1.el9_6, kernel-64k 5.14.0-570.142.1.el9_6, kernel-core 5.14.0-570.142.1.el9_6, kernel-tools 5.14.0-570.142.1.el9_6, kernel-modules 5.14.0-570.142.1.el9_6, kernel-64k-core 5.14.0-570.142.1.el9_6, +27 more
    fixed: vendor fix RHSA-2026:70484
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.38.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.38.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.38.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.38.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.38.1.el9_8
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.46.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.46.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.46.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.46.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.46.1.el10_2
    fixed: vendor fix RHSA-2026:53330
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.108.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.108.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.108.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.108.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.108.1.el10_0
    fixed: vendor fix RHSA-2026:75560
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.38.1.el9_8, kernel-rt-64k 5.14.0-687.38.1.el9_8, kernel-rt-core 5.14.0-687.38.1.el9_8, kernel-rt-modules 5.14.0-687.38.1.el9_8, kernel-rt-64k-core 5.14.0-687.38.1.el9_8, kernel-rt-debug-core 5.14.0-687.38.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.46.1.el10_2, kernel-rt-64k 6.12.0-211.46.1.el10_2, kernel-rt-core 6.12.0-211.46.1.el10_2, kernel-rt-modules 6.12.0-211.46.1.el10_2, kernel-rt-64k-core 6.12.0-211.46.1.el10_2, kernel-rt-debug-core 6.12.0-211.46.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:53330
  • Red Hat Enterprise Linux Real Time E4S (v.9.4) kernel-rt 5.14.0-427.151.1.el9_4, kernel-rt-core 5.14.0-427.151.1.el9_4, kernel-rt-modules 5.14.0-427.151.1.el9_4, kernel-rt-debug-core 5.14.0-427.151.1.el9_4, kernel-rt-modules-core 5.14.0-427.151.1.el9_4, kernel-rt-debug-modules 5.14.0-427.151.1.el9_4, +4 more
    fixed: vendor fix RHSA-2026:69908
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.108.1.el10_0, kernel-rt-64k 6.12.0-55.108.1.el10_0, kernel-rt-core 6.12.0-55.108.1.el10_0, kernel-rt-modules 6.12.0-55.108.1.el10_0, kernel-rt-64k-core 6.12.0-55.108.1.el10_0, kernel-rt-debug-core 6.12.0-55.108.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:75560
  • Red Hat Enterprise Linux Real Time EUS (v.9.6) kernel-rt 5.14.0-570.142.1.el9_6, kernel-rt-64k 5.14.0-570.142.1.el9_6, kernel-rt-core 5.14.0-570.142.1.el9_6, kernel-rt-modules 5.14.0-570.142.1.el9_6, kernel-rt-64k-core 5.14.0-570.142.1.el9_6, kernel-rt-debug-core 5.14.0-570.142.1.el9_6, +14 more
    fixed: vendor fix RHSA-2026:70484
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.38.1.el9_8, kernel-rt-core 5.14.0-687.38.1.el9_8, kernel-rt-modules 5.14.0-687.38.1.el9_8, kernel-rt-debug-core 5.14.0-687.38.1.el9_8, kernel-rt-modules-core 5.14.0-687.38.1.el9_8, kernel-rt-debug-modules 5.14.0-687.38.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.46.1.el10_2, kernel-rt-core 6.12.0-211.46.1.el10_2, kernel-rt-modules 6.12.0-211.46.1.el10_2, kernel-rt-debug-core 6.12.0-211.46.1.el10_2, kernel-rt-modules-core 6.12.0-211.46.1.el10_2, kernel-rt-debug-modules 6.12.0-211.46.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:53330
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4) kernel-rt 5.14.0-427.151.1.el9_4, kernel-rt-kvm 5.14.0-427.151.1.el9_4, kernel-rt-core 5.14.0-427.151.1.el9_4, kernel-rt-modules 5.14.0-427.151.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.151.1.el9_4, kernel-rt-debug-core 5.14.0-427.151.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:69908
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.108.1.el10_0, kernel-rt-kvm 6.12.0-55.108.1.el10_0, kernel-rt-core 6.12.0-55.108.1.el10_0, kernel-rt-modules 6.12.0-55.108.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.108.1.el10_0, kernel-rt-debug-core 6.12.0-55.108.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:75560
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) kernel-rt 5.14.0-570.142.1.el9_6, kernel-rt-kvm 5.14.0-570.142.1.el9_6, kernel-rt-core 5.14.0-570.142.1.el9_6, kernel-rt-modules 5.14.0-570.142.1.el9_6, kernel-rt-debug-kvm 5.14.0-570.142.1.el9_6, kernel-rt-debug-core 5.14.0-570.142.1.el9_6, +6 more
    fixed: vendor fix RHSA-2026:70484
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.