CVE-2021-38198

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LowLow ImpactWhat does this mean?

6.4CVSS v3 Score Breakdown

Description

Statement

Mitigation

Additional information

Affected Packages

CVSS Score Details

Weakness (CWE)

FAQ

Description

A flaw was found in the Linux kernel, where it incorrectly computes the access permissions of a shadow page. This issue leads to a missing guest protection page fault.

Statement

The issue is rated as having Low impact because the issue is not present when hardware-assisted paging (also known as nested paging and Second Level Address Translation) is enabled. Hardware-assisted paging is enabled by default for CPUs that support it. Any realistic real-life virtualization scenario benefits greatly from hardware assisted paging speed up, so deployments without hardware-assisted paging are very rare.

Mitigation

Do not disable hardware-assisted paging (also known as nested paging and Second Level Address Translation) on your hosts. The default is on.

Additional information

Bugzilla 1992264: kernel: arch/x86/kvm/mmu/paging_tmpl.h incorrectly computes the access permissions of a shadow page
CWE-732: Incorrect Permission Assignment for Critical Resource
FAQ: Frequently asked questions about CVE-2021-38198

External references

https://www.cve.org/CVERecord?id=CVE-2021-38198

https://nvd.nist.gov/vuln/detail/CVE-2021-38198

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 Score Breakdown
	Red Hat	NVD
CVSS v3 Base Score	6.4	5.5
Attack Vector	Local	Local
Attack Complexity	High	Low
Privileges Required	High	Low
User Interaction	None	None
Scope	Unchanged	Unchanged
Confidentiality Impact	High	None
Integrity Impact	High	None
Availability Impact	High	High

CVSS v3 Vector

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

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

Understanding the Weakness (CWE)

CWE-732

Confidentiality

Technical Impact: Read Application Data; Read Files or Directories

An attacker may be able to read sensitive information from the associated resource, such as credentials or configuration information stored in a file.

Access Control

Technical Impact: Gain Privileges or Assume Identity

An attacker may be able to modify critical properties of the associated resource to gain privileges, such as replacing a world-writable executable with a Trojan horse.

Integrity,Other

Technical Impact: Modify Application Data; Other

An attacker may be able to destroy or corrupt critical data in the associated resource, such as deletion of records from a database.

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

"Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
The term "Affected" means that our Analysis team has determined that this product, such as Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to address this issue in the near future. This includes all minor releases of this product unless noted otherwise in the Statement text.

What can I do if my product is listed as "Will not fix"?

A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:

Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
Apply a mitigation (if one exists).
Open a support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:

Apply a mitigation (if one exists).
Open a support case to request a prioritization of releasing a fix for this vulnerability.
Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

I have a Red Hat product but it is not in the above list, is it affected?

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our Red Hat Vulnerability Scanner Certification program.

My product is listed as "Out of Support Scope". What does this mean?

When a product is listed as "Out of Support Scope", it means a vulnerability with the impact level assigned to this CVE is no longer covered by its current support lifecycle phase. The product has been identified to contain the impacted component, but analysis to determine whether it is affected or not by this vulnerability was not performed. The product should be assumed to be affected. Customers are advised to apply any mitigation options documented on this page, consider removing or disabling the impacted component, or upgrade to a supported version of the product that has an update available.

Not sure what something means? Check out our Security Glossary.

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CVE-2021-38198

Description

Statement

Mitigation

Additional information

External references

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS v3 Vector

Understanding the Weakness (CWE)

Confidentiality

Access Control

Integrity,Other

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

What can I do if my product is listed as "Will not fix"?

What can I do if my product is listed as "Fix deferred"?

What is a mitigation?

I have a Red Hat product but it is not in the above list, is it affected?

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

My product is listed as "Out of Support Scope". What does this mean?

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