CVE-2025-21792 is a vulnerability in the Linux kernel's AX25 protocol implementation where a reference count leak occurs when binding an AX25 device to a socket using the SO_BINDTODEVICE socket option. This leak happens because the reference count increment is missing in this code path, leading to improper resource management and potential memory leaks. The issue was identified and fixed by ensuring that reference counts are correctly incremented and decremented when devices are bound or unbound from sockets.