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Fencer Vulns
medium 5.5

CVE-2021-43056 json

An issue was discovered in the Linux kernel for powerpc before 5.14.15.

published 2021-10-28 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-30009

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

An issue was discovered in the Linux kernel for powerpc before 5.14.15. It allows a malicious KVM guest to crash the host, when the host is running on Power8, due to an arch/powerpc/kvm/book3s_hv_rmhandlers.S implementation bug in the handling of the SRR1 register values.

Patch / fix

  • linux linux_kernel 5.4.15
  • linux Debian 14, Debian 13, Debian 12 5.14.16-1

debian advisories DEBIAN-CVE-2021-43056

  • linux Ubuntu 20.04 LTS 5.4.0-92.103
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1061.64
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1059.63
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1057.60
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1010.11
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1051.53
  • linux-azure Ubuntu 20.04 LTS 5.4.0-1065.68
  • linux-gkeop Ubuntu 20.04 LTS 5.4.0-1029.30

ubuntu advisories UBUNTU-CVE-2021-43056

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 8 4.18.0-372.9.1.el8
  • perf RHEL 8 4.18.0-372.9.1.el8
  • bpftool RHEL 8 4.18.0-372.9.1.el8
  • kernel-core RHEL 8 4.18.0-372.9.1.el8
  • kernel-tools RHEL 8 4.18.0-372.9.1.el8
  • python3-perf RHEL 8 4.18.0-372.9.1.el8
  • kernel-modules RHEL 8 4.18.0-372.9.1.el8
  • kernel-zfcpdump RHEL 8 4.18.0-372.9.1.el8

red hat advisories RHSA-2022:1988

  • kernel-64kb SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS, SLE High Performance Computing 15 SP4-ESPOS 5.14.21-150400.24.122.2
  • kernel-syms SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +3 more 5.14.21-150400.24.122.1
  • kernel-source SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +3 more 5.14.21-150400.24.122.1
  • kernel-default SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +9 more 5.14.21-150400.24.122.2
  • kernel-zfcpdump SLES 15 SP4-LTSS, Manager Server 4.3 5.14.21-150400.24.122.2
  • kernel-obs-build SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +1 more 5.14.21-150400.24.122.2
  • kernel-default-base SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +7 more 5.14.21-150400.24.122.2.150400.24.58.2
  • kernel-64kb SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS, Enterprise Storage 7.1 5.3.18-150300.59.164.1

suse advisories SUSE-SU-2024:2189-1SUSE-SU-2024:2185-1SUSE-SU-2024:2183-1SUSE-SU-2024:2010-1SUSE-SU-2024:2008-1SUSE-SU-2021:3754-1

  • dtb-aarch64 openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-64kb openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-syms openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-obs-qa openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-source openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-default openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-preempt openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-kvmsmall openSUSE Leap 15.3 5.3.18-59.34.1

opensuse advisories openSUSE-SU-2021:3675-1openSUSE-SU-2021:1477-1openSUSE-SU-2021:3641-1

  • kernel AlmaLinux 8 4.18.0-372.9.1.el8
  • perf AlmaLinux 8 4.18.0-372.9.1.el8
  • bpftool AlmaLinux 8 4.18.0-372.9.1.el8
  • kernel-core AlmaLinux 8 4.18.0-372.9.1.el8
  • kernel-tools AlmaLinux 8 4.18.0-372.9.1.el8
  • python3-perf AlmaLinux 8 4.18.0-372.9.1.el8
  • kernel-modules AlmaLinux 8 4.18.0-372.9.1.el8
  • kernel-debug-core AlmaLinux 8 4.18.0-372.9.1.el8

almalinux advisories ALSA-2022:1988

  • kernel Rocky Linux 8 4.18.0-372.9.1.el8

rocky linux advisories RLSA-2022:1988

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-2021-43056 updated cvss 5.5

kernel: ppc: kvm: allows a malicious KVM guest to crash the host

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, python-perf, kernel-kdump, kernel-tools, +3 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-372.9.1.el8, kernel 4.18.0-372.9.1.el8, bpftool 4.18.0-372.9.1.el8, kernel-core 4.18.0-372.9.1.el8, kernel-tools 4.18.0-372.9.1.el8, python3-perf 4.18.0-372.9.1.el8, +15 more Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-372.9.1.el8, kernel-debuginfo-common-aarch64 4.18.0-372.9.1.el8, kernel-debuginfo-common-ppc64le 4.18.0-372.9.1.el8
    fixed: vendor fix RHSA-2022:1988
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 kernel-rt, kernel-rt-kvm, kernel-rt-trace, kernel-rt-debug-kvm, kernel-rt-trace-kvm Red Hat Enterprise Linux 8 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +6 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 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

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.9 AV:L/AC:L/Au:N/C:N/I:N/A:C

Classification

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.