Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-63992

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
19/07/2026
Last modified:
30/07/2026

Description

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> tunnels: do not assume transport header in iptunnel_pmtud_check_icmp()<br /> <br /> In some cases, iptunnel_pmtud_check_icmp() can be called while<br /> skb transport header is not set.<br /> <br /> This triggers an out-of-bound access, because<br /> (typeof(skb-&gt;transport_header))~0U is 65535.<br /> <br /> Access the icmp header based on IPv4 network header,<br /> after making sure icmp-&gt;type is present in skb linear part.<br /> <br /> Note that iptunnel_pmtud_check_icmpv6()) is fine.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 9.10 CRITICAL
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): None
Availability (A): High

Base Score 3.x
9.10
Severity 3.x
CRITICAL

References to Advisories, Solutions, and Tools