CVE-2026-63993

CriticalCVSS 9.8/10Last modified Oct 19, 2026

Description

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.

Metrics

CVSS 3.1 9.8/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness enumeration

CWE-416

Affected software

No affected versions have been published.

Timeline

Published
Jul 19, 2026
Last modified
Oct 19, 2026
NVD status
Modified

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CVE-2026-63993: Critical severity, CVSS 9.8 | Vulnix