CVE-2026-98417

A flaw was found in the Linux kernel's XFRM (IPsec encryption framework) subsystem. A remote attacker could exploit this issue by sending specially crafted ESP-in-TCP (Encapsulating Security Payload over Transmission Control Protocol) packets with invalid transport header offsets. This improper handling triggers kernel warning paths and packet processing errors, potentially resulting in a Denial of Service (DoS).

An Important-impact flaw was found in the Linux kernel's XFRM (IPsec) ESP-in-TCP (RFC 8229) encapsulation handling in net/xfrm/espintcp.c. When the TCP stream parser trims the TCP envelope from a received encapsulated packet, the resulting transport header offset can exceed the value the socket buffer's transport header offset field can represent. Resetting the transport header without validation truncates that offset and triggers the kernel's skb warning path, leading to packet processing errors and potentially a kernel panic. A remote, unauthenticated attacker able to send specially crafted ESP-in-TCP packets to a host configured for TCP encapsulation could exploit this flaw to cause a denial of service, with no impact on confidentiality or integrity (CVSS 3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, score 7.5). The kernel and kernel-rt packages in Red Hat Enterprise Linux 8, 9, and 10, and the kernel packages in Red Hat In-Vehicle OS 2, are affected, and a fix is being pursued for those releases. Red Hat Enterprise Linux 6 and 7 (including kernel-rt) are not affected because the ESP-in-TCP encapsulation code that contains this flaw is not present in those kernel versions.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.