The BIND resolver accepts validly-signed NSEC records where the "Next Domain Name" field points outside the signer's zone. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.
Exploitability
AV:NAC:LPR:NUI:NScope
S:CImpact
C:NI:HA:N8.6/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:NOther