Last Modified: Jun 28, 2025
Affected Product(s):
BIG-IP AFM
Known Affected Versions:
15.1.4, 15.1.4.1, 15.1.5, 15.1.5.1, 15.1.6, 15.1.6.1, 15.1.7, 15.1.8, 15.1.8.1, 15.1.8.2, 15.1.9, 15.1.9.1, 15.1.10, 15.1.10.2, 15.1.10.3, 15.1.10.4, 15.1.10.5, 15.1.10.6, 16.1.2, 16.1.2.1, 16.1.2.2, 16.1.3, 16.1.3.1, 16.1.3.2, 16.1.3.3, 16.1.3.4, 16.1.3.5, 16.1.4, 16.1.4.1, 16.1.4.2, 16.1.4.3, 16.1.5, 16.1.5.1, 16.1.5.2, 16.1.6
Fixed In:
17.1.0
Opened: Dec 29, 2021 Severity: 3-Major
When the DNS cache is activated, the NXDOMAIN DoS vector does not increase for the virtual server context. As a result, NXDOMAIN flood attack is never detected/mitigated at the virtual server context. Note this does not happen with other vectors like DNS A query flood attack, only for NXDOMAIN.
NXDOMAIN flood attack is never detected/mitigated at virtual server context.
Issue is only seen When DNS cache is activated and for NXDOMAIN Dos Vector.
N/A
Unbound is used to do the DNS query and the BIG-IP self IP is used to do the query instead of the listener at the server-side when DNS Cache is Enabled. DOS on connflow is also done at the client-side egress when DNS Cache is enabled in case of NXDOMAIN.