Last Modified: Jan 26, 2026
Affected Product(s):
BIG-IP F5OS-A, F5OS-C
Known Affected Versions:
17.1.1.3, 17.1.1.4, 17.1.2, 17.1.2.1, 17.1.2.2, 17.1.3
Opened: Oct 29, 2025 Severity: 1-Blocking
F5OS hardware platforms utilizing multicast routing and PIM across multiple VLAN interfaces may forward incoming multicast traffic to multiple outgoing VLAN interfaces with incorrect VLAN tagging. This behavior can lead to the successive addition of VLAN headers, resulting in a cascading accumulation of VLAN tags.
Multicast traffic dropped on VLAN interfaces receiving more than 1 VLAN tagging in the packet.
F5OS platforms configured with - Multicast routing enabled. - Configured with multicast protocols - PIM, OSPF etc. - 2 or more VLAN interfaces present for outgoing multicast traffic path .i.e. minimum of 3 or more VLAN interfaces configured with multicast routing, so that if one interface has incoming multicast traffic, it goes through atleast 2 or more other VLAN interfaces.
None.
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