CVE-2026-43198: Linux Kernel

Critical severity, CVSS 9.8. EPSS: 0.3% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: tcp: fix potential race in tcp_v6_syn_recv_sock() Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock() is done too late. After tcp_v4_syn_recv_sock(), the child socket is already visible from TCP ehash table and other cpus might use it. Since newinet->pinet6 is still pointing to the listener ipv6_pinfo bad things can happen as syzbot found. Move the problematic code in tcp_v6_mapped_child_init() and call this new helper from tcp_v4_syn_recv_sock() before the ehash insertion. This allows the removal of one tcp_sync_mss(), since tcp_v4_syn_recv_sock() will call it with the correct context.

Affected products

• Linux Linux Kernel: from 2.6.12.1, before 6.18.16 (fixed in 6.18.16); from 6.19, before 6.19.6 (fixed in 6.19.6); version 2.6.12 only; version 7.0 only

Published 2026-05-06. Last modified 2026-09-14.