CVE-2026-98432

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

ipv4: free inet_opt and ireq_opt after an RCU grace period

tcp_v4_syn_recv_sock() transfers ownership of ireq->ireq_opt to the

child socket (newinet->inet_opt) without copying it.

Another cpu can concurrently process a retransmitted SYN for the same

request socket, and send a SYNACK from tcp_check_req().

tcp_v4_send_synack() and inet_csk_route_req() read ireq->ireq_opt

under rcu_read_lock() only, and ip_build_and_send_pkt() and

ip_options_build() then read opt->optlen twice.

Note that the SYNACK timer itself is not an issue: it holds a

reference on its request socket, and inet_csk_reqsk_queue_drop()

calls timer_delete_sync() before the child can be freed.

Since commit 079096f103fa ("tcp/dccp: install syn_recv requests

into ehash table"), request sockets are processed without holding

the listener lock, so nothing prevents the child socket from being

freed while the SYNACK is still being built. TCP child sockets do

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References