CVE-2026-74480

Summary

In the Linux kernel, the following vulnerability has been resolved:

net: bridge: stop fast-leave after deleting a port group

br_multicast_leave_group() iterates mp->ports with pp = &p->next in its fast-leave path. After br_multicast_del_pg() 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, br_port_group_equal() 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 br_multicast_del_pg() so the loop stops before dereferencing the removed entry.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux6db6f0eae6052b70885562e1733896647ec1d807 < 159ad90cb929c033308bb39a2c5f8fbf393b77aaaffected
LinuxLinux6db6f0eae6052b70885562e1733896647ec1d807 < 4695430e8132420bf8de94da3eb36a6cf35fde6baffected
LinuxLinux6db6f0eae6052b70885562e1733896647ec1d807 < 0309ebbc570000ea0df11c06b69798e5860c5f6faffected
LinuxLinux6db6f0eae6052b70885562e1733896647ec1d807 < 4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4affected
LinuxLinux6db6f0eae6052b70885562e1733896647ec1d807 < a39789f211b8a4125f0c70e05b30cf715f4f187daffected
LinuxLinux4.11affected
LinuxLinux0 < 4.11unaffected
LinuxLinux6.6.151 <= 6.6.*unaffected
LinuxLinux6.12.103 <= 6.12.*unaffected
LinuxLinux6.18.44 <= 6.18.*unaffected
LinuxLinux7.1.8 <= 7.1.*unaffected
LinuxLinux7.2-rc6 <= *unaffected

Weaknesses

References