CVE intelligence

CVE-2026-63800

Vulnerability intelligence

Published Jul 19, 2026Sources checked Oct 28, 2026

9.8CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-63800 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Ubuntu Security Notices guidance

Vendor revision: Oct 5, 2026

This update corrects flaws in the following subsystems: - ARM64 architecture; - InfiniBand drivers; - Network drivers; - TCM subsystem; - exFAT file system; - Network file system (NFS) client; - Network file system (NFS) server daemon; - B.A.T.M.A.N.

Ubuntu Security Notices guidance

Vendor revision: Oct 2, 2026

Ubuntu Security Notices guidance

Vendor revision: Sep 30, 2026

CISA KEVNot listedBased on the latest collected catalog

EPSS0.6%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-63800?

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).

Source: NVD