CVE-2026-70637: LightFTP 2.4 Data Race Condition via ABOR Command in ftpserv.c

LightFTP through 2.4 contains multiple data race vulnerabilities in ftpserv.c that allow anonymous attackers to cause undefined behavior by issuing LIST followed by ABOR commands without authentication. The control thread closes datasocket and filefd descriptors while worker threads concurrently operate on the same fields in workerthreadcleanup, allowing stale file descriptors to be reassigned by the OS and subsequently used by worker threads on unrelated resources, resulting in potential denial of service.