A validly signed NSEC3 from an unrelated sibling zone may be accepted as an insecurity proof, downgrading a secure delegation and letting a forged unsigned answer through.
This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v3.1