Is CVE-2021-29657 in the CISA KEV catalog?

No. CVE-2021-29657 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-29657?

CVE-2021-29657 has a CVSS v3 base score of 7.4 (HIGH).

What is the EPSS score for CVE-2021-29657?

CVE-2021-29657 has an EPSS score of 0.41% (33th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-29657?

Upgrade linux on debian 11 to 5.10.28-1 or later. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2021-29657

HIGH

7.4

CVSS v3

NVD

Description

arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.

CWE-367TOCTOU Race Condition CWE-416Use After Free

How to fix

Remediation Available

linuxDebian

Fixed in:5.10.28-1CVE-2021-29657

linux-image-5.10.0-1026-oemUbuntu

Fixed in:5.10.0-1026.27USN-4948-1

linux-image-oem-20.04bUbuntu

Fixed in:5.10.0.1026.27USN-4948-1

linux-oem-5.10Ubuntu

Fixed in:5.10.0-1026.27USN-4948-1

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 ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

0.41%probability of exploitation in 30 days

33rdpercentile

Low risk: more likely to be exploited than 33% of all known CVEs.

References

Patch3

Third-Party Advisory2

Related Vulnerabilities

Other CWE-367 (TOCTOU Race Condition) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2022-36980	High	8.1	83%	-	Fix
CVE-2024-30088	High	7.0	68%	KEV + Ransom	Fix
CVE-2004-0594	Medium	5.1	55%	-	Fix
CVE-2024-50379	Critical	9.8	44%	-	Fix
CVE-2023-38146	High	8.8	39%	-	Fix
CVE-2024-0132	Critical	9.0	37%	-	Fix

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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 2024-11-21.