What is CVE-2021-47221?

CVE-2021-47221 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, classified as a Release of Invalid Pointer or Reference flaw (CWE-763), affecting Linux kernel versions from 5.7 onward and patched in 5.10.46, 5.12.13 and 5.13. CVE-2021-47221 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2021-47221?

CVE-2021-47221 has a CVSS score of 5.5 out of 10, rated Medium severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Is there a patch available for CVE-2021-47221?

Yes, CVE-2021-47221 has been patched. Fixed versions include 5.10.46, 5.12.13 and 5.13. If you are running Linux kernel 5.7 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2021-47221 actively exploited?

CVE-2021-47221 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Release of Invalid Pointer or Reference (CWE-763)?

The product attempts to return a memory resource to the system but calls the wrong release function. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/763.html

CVE-2021-47221

Medium

In the Linux kernel, the following vulnerability has been resolved: mm/slub: actually fix freelist pointer vs redzoning It turns out that SLUB redzoning ("slub_debug=Z") checks from s->object_size rather than from s->inuse (which is normally bumped to make room for the freelist pointer), so a cache created with an object size less than 24 would have the freelist pointer written beyond s->object_size, causing the redzone to be corrupted by the freelist pointer. This was very visible with "slub_debug=ZF": BUG test (Tainted: G B ): Right Redzone overwritten ----------------------------------------------------------------------------- INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200 INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620 Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........ Object (____ptrval____): 00 00 00 00 00 f6 f4 a5 ........ Redzone (____ptrval____): 40 1d e8 1a aa @.... Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........ Adjust the offset to stay within s->object_size. (Note that no caches of in this size range are known to exist in the kernel currently.)

Package Linux Kernel

Published 2024-05-21

Last modified 2025-04-29

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

5.5

out of 10

Medium

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

High

Vector string

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

Weakness type

CWE-763

CVE-2021-47221 is a Release of Invalid Pointer or Reference vulnerability

What is Release of Invalid Pointer or Reference?

The product attempts to return a memory resource to the system but calls the wrong release function. Learn more on MITRE CWE

Affected versions

Linux kernel versions 5.7 and later are affected. Fixed in 5.10.46, 5.12.13, 5.13 and their respective stable series.

Affected from

≥ 5.7

Fixed in

✓ 5.10.46 5.10.x ✓ 5.12.13 5.12.x ✓ 5.13

References

3 total

Kernel Git
https://git.kernel.org/stable/c/ce6e8bee7a3883e8008b30f5887dbb426aac6a35

Patch
Kernel Git
https://git.kernel.org/stable/c/e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8e

Patch
Kernel Git
https://git.kernel.org/stable/c/f6ed2357541612a13a5841b3af4dc32ed984a25f

Patch

Details

CVE ID CVE-2021-47221

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2024-05-21

Modified 2025-04-29

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2021-47221?

CVE-2021-47221 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as a Release of Invalid Pointer or Reference flaw (CWE-763) . It affects Linux kernel versions from 5.7 onward and has been patched in 5.10.46, 5.12.13 and 5.13. CVE-2021-47221 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2021-47221?

CVE-2021-47221 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Is there a patch available for CVE-2021-47221?

Yes. CVE-2021-47221 has been patched. Fixed versions include 5.10.46, 5.12.13 and 5.13. If you are running Linux kernel 5.7 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2021-47221 actively exploited?

No. CVE-2021-47221 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.