CVE intelligence

CVE-2026-63993

Vulnerability intelligence

Published Jul 19, 2026Sources checked Nov 10, 2026

9.8CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-63993 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

This update corrects flaws in the following subsystems: - ARM64 architecture; - InfiniBand drivers; - Network drivers; - TCM subsystem; - B.A.T.M.A.N.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.5%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-63993?

In the Linux kernel, the following vulnerability has been resolved:

vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()

skb_tunnel_check_pmtu() can change skb->head.

Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF.

Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c.

Found by Sashiko.

Source: NVD