Multiple vulnerabilities were found in nxdomain-redirect feature and simultaneous TCP connections limit of the ISC BIND software. A remote attacker could send specially crafted queries to trigger an assertion failure or exhaust the pool of file descriptors.
Successful exploitation could lead to a denial of service condition on an affected system.
Internet Systems Consortium (ISC) has released the following patches to solve the problems
http://www.isc.org/downloads/
Users of affected systems should follow the recommendations provided by the product vendor and take immediate actions to mitigate the risk.
https://kb.isc.org/docs/cve-2018-5743
https://kb.isc.org/docs/cve-2019-6467
https://kb.isc.org/docs/cve-2019-6468
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-5743
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-6467
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-6468