What is CVE-2021-47259?

CVE-2021-47259 is a High severity Linux kernel vulnerability with a CVSS score of 7.5 out of 10, classified as a Use After Free flaw (CWE-416), affecting Linux kernel versions from 4.13 onward and patched in 4.14.237, 4.19.195, 5.4.126 and others. CVE-2021-47259 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2021-47259?

CVE-2021-47259 has a CVSS score of 7.5 out of 10, rated High severity. The vector string is CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2021-47259?

Yes, CVE-2021-47259 has been patched. Fixed versions include 4.14.237, 4.19.195, 5.4.126 and others. If you are running Linux kernel 4.13 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2021-47259 actively exploited?

CVE-2021-47259 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-2021-47259

High

In the Linux kernel, the following vulnerability has been resolved: NFS: Fix use-after-free in nfs4_init_client() KASAN reports a use-after-free when attempting to mount two different exports through two different NICs that belong to the same server. Olga was able to hit this with kernels starting somewhere between 5.7 and 5.10, but I traced the patch that introduced the clear_bit() call to 4.13. So something must have changed in the refcounting of the clp pointer to make this call to nfs_put_client() the very last one.

Package Linux Kernel

Published 2024-05-21

Last modified 2025-04-04

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.5

out of 10

High

Attack Vector

Network

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Weakness type

CWE-416

CVE-2021-47259 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 4.13 and later are affected. Fixed in 4.14.237, 4.19.195, 5.4.126, 5.10.44, 5.12.11, 5.13 and their respective stable series.

Affected from

≥ 4.13

Fixed in

✓ 4.14.237 4.14.x ✓ 4.19.195 4.19.x ✓ 5.4.126 5.4.x ✓ 5.10.44 5.10.x ✓ 5.12.11 5.12.x ✓ 5.13

References

6 total

Kernel Git
https://git.kernel.org/stable/c/3e3c7ebbfac152d08be75c92802a64a1f6471a15

Patch
Kernel Git
https://git.kernel.org/stable/c/42c10b0db064e45f5c5ae7019bbf2168ffab766c

Patch
Kernel Git
https://git.kernel.org/stable/c/476bdb04c501fc64bf3b8464ffddefc8dbe01577

Patch
Kernel Git
https://git.kernel.org/stable/c/72651c6579a25317a90536181d311c663d0329ab

Patch
Kernel Git
https://git.kernel.org/stable/c/c3b6cf64dfe4ef96e7341508d50d6998da7062c7

Patch

Showing 5 of 6 references View all on NVD

Details

CVE ID CVE-2021-47259

Severity High

CVSS score 7.5 / 10

CVSS version 3.1

Published 2024-05-21

Modified 2025-04-04

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2021-47259?

CVE-2021-47259 is a High severity Linux kernel vulnerability with a CVSS score of 7.5 out of 10 , classified as an Use After Free flaw (CWE-416) . It affects Linux kernel versions from 4.13 onward and has been patched in 4.14.237, 4.19.195, 5.4.126 and others. CVE-2021-47259 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2021-47259?

CVE-2021-47259 has a CVSS score of 7.5 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2021-47259?

Yes. CVE-2021-47259 has been patched. Fixed versions include 4.14.237, 4.19.195, 5.4.126 and others. If you are running Linux kernel 4.13 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2021-47259 actively exploited?

No. CVE-2021-47259 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.