What is CVE-2026-63800?

CVE-2026-63800 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10, classified as a Use After Free flaw (CWE-416), affecting Linux kernel versions from 5.10.9 onward and patched in 5.10.260, 5.15.211, 6.1.177 and others. CVE-2026-63800 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-63800?

CVE-2026-63800 has a CVSS score of 9.8 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2026-63800?

Yes, CVE-2026-63800 has been patched. Fixed versions include 5.10.260, 5.15.211, 6.1.177 and others. If you are running Linux kernel 5.10.9 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-63800 actively exploited?

CVE-2026-63800 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-2026-63800

Critical

In the Linux kernel, the following vulnerability has been resolved: pNFS: Fix use-after-free in pnfs_update_layout() When hitting the NFS_LAYOUT_RETURN branch in pnfs_update_layout(), the code calls pnfs_prepare_to_retry_layoutget(lo). If it succeeds, pnfs_put_layout_hdr(lo) is called before trace_pnfs_update_layout(), which still references 'lo'. This results in a use-after-free when the tracepoint accesses lo's fields. Fix this by moving the tracepoint call before pnfs_put_layout_hdr(lo).

Package Linux Kernel

Published 2026-07-19

Last modified 2026-08-17

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.8

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Weakness type

CWE-416

CVE-2026-63800 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 5.10.9, 5.4.91, 5.11 and later are affected. Fixed in 5.10.260, 5.15.211, 6.1.177, 6.6.144, 6.12.95, 6.18.38, 7.1.3, 7.2 and their respective stable series.

Affected from

≥ 5.10.9 ≥ 5.4.91 ≥ 5.11

Fixed in

✓ 5.10.260 5.10.x ✓ 5.15.211 5.15.x ✓ 6.1.177 6.1.x ✓ 6.6.144 6.6.x ✓ 6.12.95 6.12.x ✓ 6.18.38 6.18.x ✓ 7.1.3 7.1.x ✓ 7.2

References

8 total

Kernel Git
https://git.kernel.org/stable/c/13e198a90ca4050f4bee8a3f23680389a6563ccc

Patch
Kernel Git
https://git.kernel.org/stable/c/1f24b8302c77dcaf79c64c073877a3b9f4dd25d2

Patch
Kernel Git
https://git.kernel.org/stable/c/200e7637f4d6a1342987045eea72641524f909dc

Patch
Kernel Git
https://git.kernel.org/stable/c/2883ddd7542b4437a2ab4908fe2773f690e20889

Patch
Kernel Git
https://git.kernel.org/stable/c/4ad8b9a85dbf57ca532ee9e65ad7e6498bfbbf98

Patch

Showing 5 of 8 references View all on NVD

Details

CVE ID CVE-2026-63800

Severity Critical

CVSS score 9.8 / 10

CVSS version 3.1

Published 2026-07-19

Modified 2026-08-17

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-63800?

CVE-2026-63800 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 , classified as an Use After Free flaw (CWE-416) . It affects Linux kernel versions from 5.10.9 onward and has been patched in 5.10.260, 5.15.211, 6.1.177 and others. CVE-2026-63800 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-63800?

CVE-2026-63800 has a CVSS score of 9.8 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2026-63800?

Yes. CVE-2026-63800 has been patched. Fixed versions include 5.10.260, 5.15.211, 6.1.177 and others. If you are running Linux kernel 5.10.9 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-63800 actively exploited?

No. CVE-2026-63800 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.