CVE-2019-5599

En FreeBSD versión 12.0-STABLE anterior a r349197 y versión 12.0-RELEASE anterior a 12.0-RELEASE-p6, un bug en la pila de RACK TCP no predeterminada puede permitir a un atacante causar que varias listas vinculadas crezcan sin límites y causar un salto de lista costoso en cada paquete procesado, lo que conlleva al agotamiento de los recursos y una denegación de servicio.

While processing acknowledgements, the RACK code uses several linked lists to maintain state entries. A malicious attacker can cause the lists to grow unbounded. This can cause an expensive list traversal on every packet being processed, leading to resource exhaustion and a denial of service. An attacker with the ability to send specially crafted TCP traffic to a victim system can degrade network performance and/or consume excessive CPU by exploiting the inefficiency of traversing the potentially very large RACK linked lists with relatively small bandwidth cost.