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Unscored CVE-2021-47255 EUVD-2021-33903GHSA-wgwm-v825-xmjx

kvm: LAPIC: Restore guard to prevent illegal APIC register access

Published May 21, 2024 · Updated May 11, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: linux Package: linux 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-5.4 Package: linux-aws-5.8 Package: linux-aws-6.2 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-5.4 Package: linux-azure-5.8 Package: linux-azure-6.2 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.2 Package: linux-azure-fips 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-5.4 Package: linux-gcp-5.8 Package: linux-gcp-6.2 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-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.19 Package: linux-hwe-5.4 Package: linux-hwe-5.8 Package: linux-hwe-6.2 Package: linux-hwe-edge Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-kvm Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.2 Package: linux-nvidia-6.2 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-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.3 Package: linux-oracle-5.4 Package: linux-oracle-5.8 Package: linux-raspi Package: linux-raspi-5.4 Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-vmware Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

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

kvm: LAPIC: Restore guard to prevent illegal APIC register access

Per the SDM, "any access that touches bytes 4 through 15 of an APIC
register may cause undefined behavior and must not be executed."
Worse, such an access in kvm_lapic_reg_read can result in a leak of
kernel stack contents. Prior to commit 01402cf81051 ("kvm: LAPIC:
write down valid APIC registers"), such an access was explicitly
disallowed. Restore the guard that was removed in that commit.

Affected products

VendorProductAffectedFixed
Linux Linux 5.3 5.4.128

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 5.10.46-1 —
Debian 13 linux 5.10.46-1 —
Debian 12 linux 5.10.46-1 —
ReleasePackageFixed inAdvisory
Ubuntu 24.04 LTS linux-raspi-realtime No fix yet —
Ubuntu 22.04 LTS linux-riscv +22 No fix yet —
Ubuntu 20.04 LTS linux 5.4.0-81.91 —
Ubuntu 20.04 LTS linux-aws 5.4.0-1055.58 —
Ubuntu 20.04 LTS linux-azure 5.4.0-1056.58 —
Ubuntu 20.04 LTS linux-bluefield 5.4.0-1019.22 —
Ubuntu 20.04 LTS linux-gcp 5.4.0-1051.55 —
Ubuntu 20.04 LTS linux-gke +26 No fix yet —
Ubuntu 20.04 LTS linux-gkeop 5.4.0-1022.23 —
Ubuntu 20.04 LTS linux-kvm 5.4.0-1045.47 —
Ubuntu 20.04 LTS linux-oracle 5.4.0-1053.57 —
Ubuntu 20.04 LTS linux-raspi 5.4.0-1042.46 —
Ubuntu 18.04 LTS linux-aws-5.4 5.4.0-1055.58~18.04.1 —
Ubuntu 18.04 LTS linux-azure-5.4 5.4.0-1056.58~18.04.1 —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 18.04 LTS linux-gcp-5.4 5.4.0-1051.55~18.04.1 —
Ubuntu 18.04 LTS linux-hwe-5.4 5.4.0-81.91~18.04.1 —
Ubuntu 18.04 LTS linux-oracle-5.4 5.4.0-1053.57~18.04.1 —
Ubuntu 18.04 LTS linux-raspi-5.4 5.4.0-1042.46~18.04.3 —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Show 2 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro FIPS 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 20.04 LTS linux-aws-fips 5.4.0-1069.73+fips2 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-azure-fips 5.4.0-1073.76+fips1 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips 5.4.0-1032.37 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-gcp-fips 5.4.0-1067.71~20.04.1 —
ReleasePackageFixed inAdvisory
SLES 15 SP3 kernel-64kb +7 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLES 15 SP3 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLES 15 SP2 kernel-default-base 5.3.18-150200.24.194.1.150200.9.99.1 SUSE-SU-2024:2183-1
SLES 15 SP2 kernel-docs +5 5.3.18-150200.24.194.1 SUSE-SU-2024:2183-1
Show 9 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 15 SP3 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLES for SAP 15 SP3 kernel-docs +5 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLES for SAP 15 SP2 kernel-default-base 5.3.18-150200.24.194.1.150200.9.99.1 SUSE-SU-2024:2183-1
SLES for SAP 15 SP2 kernel-docs +5 5.3.18-150200.24.194.1 SUSE-SU-2024:2183-1
SLE Micro 5.2 kernel-default 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLE Micro 5.2 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLE Micro 5.2 kernel-rt +1 5.3.18-150300.172.1 SUSE-SU-2025:01995-1, SUSE-SU-2024:2010-1
SLE Micro 5.1 kernel-default 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLE Micro 5.1 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLE Micro 5.1 kernel-rt +1 5.3.18-150300.172.1 SUSE-SU-2025:01995-1, SUSE-SU-2024:2010-1
SLE Live Patching 15 SP3 kernel-default 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLE Live Patching 15 SP3 kernel-livepatch-SLE15-SP3_Update_45 1-150300.7.3.1 SUSE-SU-2024:2185-1
SLE Live Patching 15 SP2 kernel-default 5.3.18-150200.24.194.1 SUSE-SU-2024:2183-1
SLE Live Patching 15 SP2 kernel-livepatch-SLE15-SP2_Update_49 1-150200.5.3.1 SUSE-SU-2024:2183-1
SLE HPC 15 SP3 kernel-64kb +6 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLE HPC 15 SP3 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLE HPC 15 SP2 kernel-default-base 5.3.18-150200.24.194.1.150200.9.99.1 SUSE-SU-2024:2183-1
SLE HPC 15 SP2 kernel-docs +5 5.3.18-150200.24.194.1 SUSE-SU-2024:2183-1
SUSE Enterprise Storage 7.1 kernel-64kb +6 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SUSE Enterprise Storage 7.1 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1

Advisories 4

References