CVE-2021-43056

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.5 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 73% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this week
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
26.7%
KEV
Not listed

Published

October 28, 2021

Last Modified

November 21, 2024

References (14)

Vendor Advisories for CVE-2021-43056(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(6)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-oem-5.14-headers-5.14.0-1008 (5.14.0-1008.8) @ focal2026-05-26ubuntu
ubuntulinux-oem-20.04b (5.10.0.1051.53) @ focal2026-05-26ubuntu
ubuntulinux-modules-extra-5.4.0-1059-gcp (5.4.0-1059.63) @ focal2026-05-26ubuntu
ubuntulinux-image-unsigned-5.13.0-1008-gcp (5.13.0-1008.9) @ impish2026-05-26ubuntu
ubuntulinux-image-5.13.0-1026-oem (5.13.0-1026.32) @ focal2026-05-26ubuntu
redhatkernel-0:4.18.0-372.9.1.el82022-05-10redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Additional Vendor Advisories

(5)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 13× in last 7d / 51× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 108 total refreshes for this CVE.

  1. 2026-07-23 02:05 UTCEG score recompute
  2. 2026-07-22 22:51 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
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  46. 2026-06-12 18:10 UTCOSV refresh
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Frequently asked(5)

What is CVE-2021-43056?
CVE-2021-43056 is a medium vulnerability published on October 28, 2021. 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/book3shvrmhandlers.S implementation bug in the handling of the SRR1 register values.
When was CVE-2021-43056 disclosed?
CVE-2021-43056 was first published in the National Vulnerability Database on October 28, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-43056 actively exploited?
CVE-2021-43056 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 26.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-43056?
CVE-2021-43056 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2021-43056?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-43056, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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