High [CVE-2026-74746] publish GC-visible tuple last

In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: publish GC-visible tuple last nf_flow_table_iterate() only treats original-direction tuple nodes as owning entries. Publishing the original node first lets GC observe and free a flow while flow_offload_add() is still inserting the reply node.

Publish the reply node first and the original node last so GC never sees a partially installed flow. KASAN can trigger slab-use-after-free read and write reports in the flowtable/rhashtable path (rht_deferred_worker, jhash, flow_offload_del, flow_offload_lookup, etc.).

This vulnerability occurs due to a timing issue where the system's garbage collection can free a network flow while it is still being set up. This can lead to a 'use-after-free' condition, where the system attempts to access memory that has already been released.

This memory corruption could potentially result in a system crash (denial of service) or, in certain circumstances, allow for arbitrary code execution. Red Hat severity: Important — CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

Weakness: CWE-825. Affected Red Hat products: Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.6 Extended Update Support; Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.