Multiple TCP Selective Acknowledgement (SACK) and Maximum Segment Size (MSS) networking vulnerabilities may cause denial-of-service conditions in Linux and FreeBSD kernels.
CVE-2019-11477: SACK Panic (Linux >= 2.6.29). A sequence of specifically crafted selective acknowledgements (SACK) may trigger an integer overflow, leading to a denial of service or possible kernel failure (panic).
CVE-2019-11478: SACK Slowness (Linux < 4.15) or Excess Resource Usage (all Linux versions). A sequence of specifically crafted selective acknowledgements (SACK) may cause a fragmented TCP queue, with a potential result in slowness or denial of service.
A remote attacker could cause a kernel crash (CVE-2019-11477) or excessive resource consumption leading to a delay or denial of service.
Several vendors have issued workarounds. See the vendor list below for details from specific vendors.
Jonathan Looney(Netflix Information Security)