Is CVE-2021-47450 in the CISA KEV catalog?

No. CVE-2021-47450 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-47450?

CVE-2021-47450 has a CVSS v3 base score of 5.5 (MEDIUM).

What is the EPSS score for CVE-2021-47450?

CVE-2021-47450 has an EPSS score of 0.20% (10th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-47450?

Upgrade linux on debian 12 to 5.15.3-1 or later.

CVE & CISA-KEV Catalog

CVE-2021-47450

MEDIUM

5.5

CVSS v3

NVD

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Fix host stage-2 PGD refcount The KVM page-table library refcounts the pages of concatenated stage-2 PGDs individually. However, when running KVM in protected mode, the host's stage-2 PGD is currently managed by EL2 as a single high-order compound page, which can cause the refcount of the tail pages to reach 0 when they shouldn't, hence corrupting the page-table. Fix this by introducing a new hyp_split_page() helper in the EL2 page allocator (matching the kernel's split_page() function), and make use of it from host_s2_zalloc_pages_exact().

How to fix

Remediation Available

linuxDebian

Fixed in:5.15.3-1CVE-2021-47450

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploit Intelligence

0.20%probability of exploitation in 30 days

10thpercentile

Low risk: more likely to be exploited than 10% of all known CVEs.

References

Patch2

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-09-24.