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Unscored CVE-2026-64369 EUVD-2026-48913GHSA-ww8w-mgxm-5cf5

s390: Revert support for DCACHE_WORD_ACCESS

Published Jul 25, 2026 · Updated Nov 6, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: linux Package: linux Package: linux-6.12 Package: linux-allwinner-5.19 Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.8 Package: linux-aws-6.14 Package: linux-aws-6.17 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 Package: linux-aws-7.0 Package: linux-aws-fips Package: linux-azure Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.8 Package: linux-azure-6.11 Package: linux-azure-6.14 Package: linux-azure-6.17 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-7.0 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.17 Package: linux-azure-fde-6.2 Package: linux-azure-fde-6.8 Package: linux-azure-fde-7.0 Package: linux-azure-fips Package: linux-azure-nvidia Package: linux-azure-nvidia-6.14 Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.8 Package: linux-gcp-6.11 Package: linux-gcp-6.14 Package: linux-gcp-6.17 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 Package: linux-gcp-7.0 Package: linux-gcp-fips Package: linux-gke Package: linux-gke-4.15 Package: linux-gke-5.15 Package: linux-gke-5.4 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-gkeop-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.19 Package: linux-hwe-5.8 Package: linux-hwe-6.11 Package: linux-hwe-6.14 Package: linux-hwe-6.17 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-7.0 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-6.8 Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-lowlatency Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.11 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-lowlatency-hwe-6.8 Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.17 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-7.0 Package: linux-nvidia-bos Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-oem Package: linux-oem-5.10 Package: linux-oem-5.13 Package: linux-oem-5.14 Package: linux-oem-5.17 Package: linux-oem-5.6 Package: linux-oem-6.0 Package: linux-oem-6.1 Package: linux-oem-6.11 Package: linux-oem-6.14 Package: linux-oem-6.17 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oem-7.0 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.3 Package: linux-oracle-5.8 Package: linux-oracle-6.14 Package: linux-oracle-6.17 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-oracle-7.0 Package: linux-raspi Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.14 Package: linux-realtime-6.17 Package: linux-realtime-6.8 Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.14 Package: linux-riscv-6.17 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-riscv-7.0 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-vmware Package: linux-xilinx Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

In the Linux kernel, the following vulnerability has been resolved:

s390: Revert support for DCACHE_WORD_ACCESS

load_unaligned_zeropad() reads eight bytes from unaligned addresses and may
cross page boundaries. It handles exceptions which may happen if reading
from the second page results in an exception.

For pages which are donated to the Ultravisor for secure execution purposes
the do_secure_storage_access() exception handler however does not handle
such exceptions correctly. Such an exception may result in an endless
exception loop which will never be resolved.

An attempt to fix this [1] turned out to be not sufficient. For now revert
load_unaligned_zeropad() until this problem has been resolved in a proper
way.

Note that the implementation of load_unaligned_zeropad() itself is
correct. The revert is just a temporary workaround until there is complete
fix for secure storage access exceptions.

[1] commit b00be77302d7 ("s390/mm: Add missing secure storage access fixups for donated memory")

Affected products

VendorProductAffectedFixed
Linux Linux 6.7 6.12.97

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 linux 7.1.4-1 —
Debian 13 linux 6.12.100-1 —
Debian 12 linux-6.12 6.12.100-1~deb12u1 —
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield 6.8.0-1033.38 —
Ubuntu 26.04 LTS linux 7.0.0-31.31 USN-8726-1
Ubuntu 26.04 LTS linux-aws 7.0.0-1012.12 USN-8726-1
Ubuntu 26.04 LTS linux-azure 7.0.0-1014.14 USN-8726-4
Ubuntu 26.04 LTS linux-gcp +1 7.0.0-1011.11 USN-8726-4, USN-8726-1
Ubuntu 26.04 LTS linux-gke 7.0.0-1006.7 USN-8726-1
Ubuntu 26.04 LTS linux-ibm +2 7.0.0-1013.13 USN-8727-1, USN-8726-3
Ubuntu 26.04 LTS linux-nvidia 7.0.0-1018.18 USN-8760-2
Ubuntu 26.04 LTS linux-nvidia-bos 7.0.0-2018.18 USN-8800-1
Ubuntu 26.04 LTS linux-raspi 7.0.0-1019.19 USN-8726-2
Ubuntu 26.04 LTS linux-riscv +1 7.0.0-31.31.1 USN-8726-1
Ubuntu 24.04 LTS linux 6.8.0-147.147 USN-8917-1
Ubuntu 24.04 LTS linux-aws +1 6.8.0-1067.70 USN-9024-1, USN-8917-1
Ubuntu 24.04 LTS linux-aws-7.0 7.0.0-1012.12~24.04.1 USN-8726-1
Ubuntu 24.04 LTS linux-azure-7.0 7.0.0-1014.14~24.04.1 USN-8728-2
Ubuntu 24.04 LTS linux-azure-fde 6.8.0-1069.76 USN-8918-1
Ubuntu 24.04 LTS linux-azure-fde-7.0 7.0.0-1013.13~24.04.1 —
Ubuntu 24.04 LTS linux-gcp +1 6.8.0-1071.79 USN-8918-1, USN-8917-1
Ubuntu 24.04 LTS linux-gcp-7.0 +1 7.0.0-1011.11~24.04.1 USN-8728-3, USN-8728-1
Ubuntu 24.04 LTS linux-gke 6.8.0-1066.74 USN-8917-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1052.56 USN-8917-1
Ubuntu 24.04 LTS linux-hwe-7.0 7.0.0-31.31~24.04.1 USN-8726-1
Ubuntu 24.04 LTS linux-ibm 6.8.0-1067.68 USN-8917-1
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-147.147.1 USN-8917-1
Ubuntu 24.04 LTS linux-nvidia-7.0 7.0.0-1018.18~24.04.1 USN-8760-1
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1067.70.1 USN-9040-1
Ubuntu 24.04 LTS linux-oracle 6.8.0-1064.67 USN-8917-1
Ubuntu 24.04 LTS linux-raspi 6.8.0-1068.72 USN-9025-1
Ubuntu 24.04 LTS linux-riscv +30 No fix yet —
Ubuntu 24.04 LTS linux-riscv-7.0 7.0.0-31.31.1~24.04.1 —
Ubuntu 24.04 LTS linux-vmware 6.8.0-1008.8 —
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1069.74~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1073.82~22.04.1 USN-9026-1
Ubuntu 22.04 LTS linux-azure-fde-6.8 6.8.0-1071.78~22.04.1 USN-9026-1
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1073.81~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-hwe-6.8 6.8.0-149.149~22.04.1 USN-9066-1
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1069.70~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-149.149.1~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1067.71~22.04.1 USN-9025-1
Ubuntu 22.04 LTS linux-riscv +33 No fix yet —
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Show 5 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-raspi-realtime 6.8.0-2056.58 USN-9025-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1062.63 USN-8917-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 +1 No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1064.65~22.04.1 USN-9024-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-aws-fips 6.8.0-1067.70+fips1 USN-8917-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-147.147+fips1 USN-8917-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips +1 6.8.0-1071.79+fips1 USN-8918-1, USN-8917-1
ReleasePackageFixed inAdvisory
openSUSE Tumbleweed kernel-source 7.1.7-1.1 openSUSE-SU-2026:11476-1

Advisories 20

References