CVE-2026-63992

CriticalCVSS 9.1/10Last modified Oct 19, 2026

Description

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

tunnels: do not assume transport header in iptunnel_pmtud_check_icmp()

In some cases, iptunnel_pmtud_check_icmp() can be called while skb transport header is not set.

This triggers an out-of-bound access, because (typeof(skb->transport_header))~0U is 65535.

Access the icmp header based on IPv4 network header, after making sure icmp->type is present in skb linear part.

Note that iptunnel_pmtud_check_icmpv6()) is fine.

Metrics

CVSS 3.1 9.1/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Weakness enumeration

CWE-125

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-2026-63992: Critical severity, CVSS 9.1 | Vulnix