DEBIAN-CVE-2026-74480

In the Linux kernel, the following vulnerability has been resolved:  net: bridge: stop fast-leave after deleting a port group  brmulticastleavegroup() iterates mp->ports with pp = &p->next in its fast-leave path. After brmulticastdelpg() removes p, continuing the loop advances pp through the deleted entry.  If multicast-to-unicast was enabled, the bridge can hold multiple port groups for the same port and group with different source MAC addresses. Once multicast-to-unicast is disabled, brportgroupequal() matches those entries by port only. A fast leave can then delete one entry and continue from its stale next pointer, leaving mp->ports pointing at a deleted port group.  Fast leave only needs to remove one matching port group. Break after brmulticastdelpg() so the loop stops before dereferencing the removed entry.