A use-after-return vulnerability exists in the named server when handling DNS queries signed with SIG(0). Using a specially-crafted DNS request, an attacker may be able to cause an ACL to improperly (mis)match an IP address. In a default-allow ACL (denying only specific IP addresses), this may lead to unauthorized access. Default-deny ACLs should fail-secure.
This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1.
BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.
Exploitability
AV:NAC:LPR:LUI:NScope
S:UImpact
C:LI:LA:N5.4/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N