CVE-2026-64422

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes<br /> <br /> Reject invalid `net.ipv4.tcp_reordering` values before they reach TCP<br /> socket state. The sysctl is stored as an `int` but copied into the<br /> `u32` `tp-&gt;reordering` field for new sockets, so negative writes wrap<br /> to large values.<br /> <br /> With `tcp_mtu_probing=2`, the wrapped value can overflow the<br /> `tcp_mtu_probe()` size calculation and drive the MTU probing path into<br /> an out-of-bounds read. Route `tcp_reordering` writes through<br /> `proc_dointvec_minmax()` and require it to be at least 1. Also require<br /> `tcp_max_reordering` to be at least 1 so the configured maximum cannot<br /> become negative either.<br /> <br /> When registering the table for a non-init network namespace, relocate<br /> `extra2` pointers that refer into `init_net.ipv4` so the<br /> `tcp_reordering` upper bound follows that namespace&amp;#39;s<br /> `tcp_max_reordering`.<br /> <br /> Harden `tcp_mtu_probe()` itself by computing `size_needed` as `u64`.<br /> This keeps the send queue and window checks from being bypassed through<br /> signed integer overflow.