What is CVE-2021-28691?

CVE-2021-28691 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10, classified as a Use After Free flaw (CWE-416), affecting Linux kernel versions from 5.5.0 onward and patched in next of 5.12.2. CVE-2021-28691 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2021-28691?

CVE-2021-28691 has a CVSS score of 7.8 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2021-28691?

Yes, CVE-2021-28691 has been patched. Fixed versions include next of 5.12.2. If you are running Linux kernel 5.5.0 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2021-28691 actively exploited?

CVE-2021-28691 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Use After Free (CWE-416)?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/416.html

CVE-2021-28691

High

Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer.

Package Linux Kernel

Published 2021-06-29

Last modified 2024-11-21

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.8

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Weakness type

CWE-416

CVE-2021-28691 is a Use After Free vulnerability

What is Use After Free?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. Learn more on MITRE CWE

Affected versions

Linux kernel versions 5.5.0 and later are affected. Fixed in next of 5.12.2 and their respective stable series.

Affected from

≥ 5.5.0

Fixed in

✓ next of 5.12.2

References

3 total

Security
https://security.gentoo.org/glsa/202107-30

Third Party Advisory
Security
https://security.netapp.com/advisory/ntap-20210805-0002/

Third Party Advisory
Xenbits
https://xenbits.xenproject.org/xsa/advisory-374.txt

Third Party Advisory

Details

CVE ID CVE-2021-28691

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2021-06-29

Modified 2024-11-21

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2021-28691?

CVE-2021-28691 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Use After Free flaw (CWE-416) . It affects Linux kernel versions from 5.5.0 onward and has been patched in next of 5.12.2. CVE-2021-28691 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2021-28691?

CVE-2021-28691 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2021-28691?

Yes. CVE-2021-28691 has been patched. Fixed versions include next of 5.12.2. If you are running Linux kernel 5.5.0 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2021-28691 actively exploited?

No. CVE-2021-28691 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.