Technical Summary

The Linux kernel vulnerability CVE-2026-43025 involves the netfilter ctnetlink subsystem where explicit helpers suggested by userspace for new expectations were not properly validated, causing a slab-out-of-bounds read in nf_ct_expect_related_report. This allowed reading kernel memory bytes beyond the expectation boundary. The fix involves ignoring explicit helpers other than the existing master conntrack helper to prevent complicated validation and memory corruption. The vulnerability has a CVSS 3.1 score of 7.3 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H), indicating local attack vector with low complexity, requiring low privileges, no user interaction, and resulting in high confidentiality and availability impact with limited integrity impact. The issue affects Linux kernel versions prior to 6.8.0-1061.64~22.04.1 and related Ubuntu kernel builds. The vendor advisory confirms a patch is available and recommends updating and rebooting the system. No exploits in the wild are currently known.