BIND was improperly sequencing cleanup operations on upstream recursion fetch contexts, leading in some cases to a use-after-free error that can trigger an assertion failure and crash in named. Affects BIND 9.0.0 to 9.8.x, 9.9.0 to 9.9.11, 9.10.0 to 9.10.6, 9.11.0 to 9.11.2, 9.9.3-S1 to 9.9.11-S1, 9.10.5-S1 to 9.10.6-S1, 9.12.0a1 to 9.12.0rc1.
https://www.debian.org/security/2018/dsa-4089
https://security.netapp.com/advisory/ntap-20180117-0003/
https://lists.debian.org/debian-lts-announce/2018/01/msg00029.html
https://kb.isc.org/docs/aa-01542
https://access.redhat.com/errata/RHSA-2018:0488
https://access.redhat.com/errata/RHSA-2018:0487
https://access.redhat.com/errata/RHSA-2018:0102
https://access.redhat.com/errata/RHSA-2018:0101