CVE-2026-80850

A flaw was found in the Linux kernel's TCP Authentication Option (TCP-AO) implementation. An unprivileged local attacker could exploit a race condition when a network device is detached from its Virtual Routing and Forwarding (VRF) interface. This could lead to a use-after-free vulnerability, causing a system crash and resulting in a Denial of Service (DoS).

A use-after-free vulnerability in the Linux kernel's TCP Authentication Option (TCP-AO) implementation, rated IMPORTANT by Red Hat Product Security with a Red Hat CVSS 3.1 score of 7.0 (AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). When TCP-AO is configured on a socket, a race condition between connection establishment and detaching the bound network device from its Virtual Routing and Forwarding (VRF) interface can make tcp_ao_connect_init() remove the only matching AO key and directly free the socket's AO information while the receive path can still access the freed structure under RCU, resulting in a use-after-free write in tcp_inbound_ao_hash(). An unprivileged local attacker able to create user and network namespaces could win this race by racing connect() against detaching a device from its VRF while TCP-AO traffic is processed, crashing the kernel and causing a denial of service; exploitation requires winning a narrow timing race, reflected in the high attack complexity of the CVSS score. In Red Hat Enterprise Linux 9.10, the kernel and kernel-rt packages are affected and a fix is being pursued for that stream. The other Red Hat Enterprise Linux versions and update streams, the Red Hat In-Vehicle OS releases, and the OpenShift Container Platform releases covered by this flaw are not affected because the vulnerable code is not present in their shipped kernels.

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.