Search: CVE-2025-40186

A high-severity vulnerability in the Linux kernel's TCP stack was resolved by removing a problematic call to reqsk_fastopen_remove() in tcp_conn_request(). The flaw caused a reference count underflow and double-free of a request socket (reqsk) when a listener socket was closed during TCP Fast Open (TFO) processing. This could lead to kernel instability or crashes. The issue was reported by syzbot and affects multiple SUSE Linux Enterprise 16 kernel live patch versions prior to 6.17.0-1007.7 and related builds. A patch is available and should be applied to mitigate the risk.