CVE-2021-43056

What it is

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.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-10-28 04:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 04:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 5.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-10-28 04:15 UTC

Last modified

2026-06-17 04:10 UTC

Exploit probability

0.4% · EPSS, next 30 days

Record status

Modified

Affected

• Linux Kernel < 5.4.15
• Fedoraproject Fedora 33
• Fedoraproject Fedora 34
• Fedoraproject Fedora 35

Attack profile CVSS 3.1 · 5.5

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-43056.md and follow it. Check whether this project is affected by CVE-2021-43056. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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