What is CVE-2021-47496?

CVE-2021-47496 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10, classified as a Out-of-bounds Write flaw (CWE-787), affecting Linux kernel versions from 4.17 onward and patched in 5.4.157, 5.10.77, 5.14.16 and others. CVE-2021-47496 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2021-47496?

CVE-2021-47496 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-2021-47496?

Yes, CVE-2021-47496 has been patched. Fixed versions include 5.4.157, 5.10.77, 5.14.16 and others. If you are running Linux kernel 4.17 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2021-47496 actively exploited?

CVE-2021-47496 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Out-of-bounds Write (CWE-787)?

The product writes data past the end or before the beginning of the intended buffer. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/787.html

CVE-2021-47496

High

In the Linux kernel, the following vulnerability has been resolved: net/tls: Fix flipped sign in tls_err_abort() calls sk->sk_err appears to expect a positive value, a convention that ktls doesn't always follow and that leads to memory corruption in other code. For instance, [kworker] tls_encrypt_done(..., err=<negative error from crypto request>) tls_err_abort(.., err) sk->sk_err = err; [task] splice_from_pipe_feed ... tls_sw_do_sendpage if (sk->sk_err) { ret = -sk->sk_err; // ret is positive splice_from_pipe_feed (continued) ret = actor(...) // ret is still positive and interpreted as bytes // written, resulting in underflow of buf->len and // sd->len, leading to huge buf->offset and bogus // addresses computed in later calls to actor() Fix all tls_err_abort() callers to pass a negative error code consistently and centralize the error-prone sign flip there, throwing in a warning to catch future misuse and uninlining the function so it really does only warn once.

Package Linux Kernel

Published 2024-05-22

Last modified 2025-09-24

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-787

CVE-2021-47496 is a Out-of-bounds Write vulnerability

What is Out-of-bounds Write?

The product writes data past the end or before the beginning of the intended buffer. Learn more on MITRE CWE

Affected versions

Linux kernel versions 4.17 and later are affected. Fixed in 5.4.157, 5.10.77, 5.14.16, 5.15 and their respective stable series.

Affected from

≥ 4.17

Fixed in

✓ 5.4.157 5.4.x ✓ 5.10.77 5.10.x ✓ 5.14.16 5.14.x ✓ 5.15

References

4 total

Kernel Git
https://git.kernel.org/stable/c/da353fac65fede6b8b4cfe207f0d9408e3121105

Patch
Kernel Git
https://git.kernel.org/stable/c/e0cfd5159f314d6b304d030363650b06a2299cbb

Patch
Kernel Git
https://git.kernel.org/stable/c/e41473543f75f7dbc5d605007e6f883f1bd13b9a

Patch
Kernel Git
https://git.kernel.org/stable/c/f3dec7e7ace38224f82cf83f0049159d067c2e19

Patch

Details

CVE ID CVE-2021-47496

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2024-05-22

Modified 2025-09-24

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2021-47496?

CVE-2021-47496 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Out-of-bounds Write flaw (CWE-787) . It affects Linux kernel versions from 4.17 onward and has been patched in 5.4.157, 5.10.77, 5.14.16 and others. CVE-2021-47496 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2021-47496?

CVE-2021-47496 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-2021-47496?

Yes. CVE-2021-47496 has been patched. Fixed versions include 5.4.157, 5.10.77, 5.14.16 and others. If you are running Linux kernel 4.17 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2021-47496 actively exploited?

No. CVE-2021-47496 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.