CVE-2026-74268 tcp: clear sock_ops cb flags before force-closing a child socket
A race condition in Linux kernel TCP handling can cause a kernel warning and potential denial of service when BPF sock_ops flags are inherited by failed child sockets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74268?
CVE-2026-74268 is a critical vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
tcp: clear sock_ops cb flags before force-closing a child socket
A child socket inherits the listener's bpf_sock_ops_cb_flags via sk_clone_lock(). If its setup fails in tcp_v4_syn_recv_sock() / tcp_v6_syn_recv_sock(), the child is freed through put_and_exit, where inet_csk_prepare_forced_close() drops the socket lock and tcp_done() runs without it.
If BPF_SOCK_OPS_STATE_CB_FLAG was inherited, tcp_done() -> tcp_set_state() calls tcp_call_bpf(), which expects the lock and trips sock_owned_by_me():
WARNING: include/net/sock.h:1799 at tcp_set_state+0x433/0x550 RIP: 0010:tcp_set_state+0x433/0x550 include/net/sock.h:1799 Call Trace: <IRQ> tcp_done+0xba/0x250 net/ipv4/tcp.c:5095 tcp_v4_syn_recv_sock+0x850/0xa50 net/ipv4/tcp_ipv4.c:1787 tcp_check_req+0xf30/0x1360 net/ipv4/tcp_minisocks.c:926 tcp_v4_rcv+0x1047/0x1b50 net/ipv4/tcp_ipv4.c:2164 </IRQ>
The child is freed before it is ever established, so it should run no sock_ops callback. Clear its cb flags in inet_csk_prepare_for_destroy_sock(), the common point for the IPv4, IPv6 and chtls forced-close paths and for the MPTCP ->syn_recv_sock() failure path (dispose_child), which reaches tcp_done() on a child that was never established too.
Which versions are affected by CVE-2026-74268?
How do I fix CVE-2026-74268?
Apply the vendor's patch.
Is CVE-2026-74268 being exploited?
There is no known exploitation of CVE-2026-74268 in the wild and no public exploit code.
Sources
Also known as AZL-96060, BELL-CVE-2026-74268, DEBIAN-CVE-2026-74268, GHSA-37cp-x28m-gm7h, UBUNTU-CVE-2026-74268.