Kylin Product Security is aware of this issue. Updates will be released as they become available. For additional information, please refer to the Kylin Knowledgebase article: https://access.Kylin.com/security/vulnerabilities/tcpsack
Kylin Enterprise Linux 5 is now in Maintenance Support 2 Phase of maintenance life cycle. This has been rated as having Moderate security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Kylin Enterprise Linux Life Cycle: https://access.Kylin.com/support/policy/updates/errata/.
Jonathan Looney discovered that the TCP retransmission queue implementation in tcp_fragment in the Linux kernel could be fragmented when handling certain TCP Selective Acknowledgment (SACK) sequences. A remote attacker could use this to cause a denial of service. This has been fixed in stable kernel releases 4.4.182, 4.9.182, 4.14.127, 4.19.52, 5.1.11, and is fixed in commit f070ef2ac66716357066b683fb0baf55f8191a2e.
An excessive resource consumption flaw was found in the way the Linux kernel's networking subsystem processed TCP Selective Acknowledgment (SACK) segments. While processing SACK segments, the Linux kernel's socket buffer (SKB) data structure becomes fragmented, which leads to increased resource utilization to traverse and process these fragments as further SACK segments are received on the same TCP connection. A remote attacker could use this flaw to cause a denial of service (DoS) by sending a crafted sequence of SACK segments on a TCP connection.