CVE-2026-74480

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.

CVSS v3 9.8 CRITICAL

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://git.kernel.org/stable/c/0309ebbc570000ea0df11c06b69798e5860c5f6f
https://git.kernel.org/stable/c/159ad90cb929c033308bb39a2c5f8fbf393b77aa
https://git.kernel.org/stable/c/1a109cc9890d017c41d77e6c82da739579c49f0b
https://git.kernel.org/stable/c/4695430e8132420bf8de94da3eb36a6cf35fde6b
https://git.kernel.org/stable/c/482bcb85139addb4e8ac8ed10baeda3e0aad4031
https://git.kernel.org/stable/c/4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4
https://git.kernel.org/stable/c/a39789f211b8a4125f0c70e05b30cf715f4f187d
https://git.kernel.org/stable/c/d6c32e2e25a9a06ba021030e26b6d602a277eb72

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-15 13:17

Updated : 2026-08-19 17:21

NVD link : CVE-2026-74480

Mitre link : CVE-2026-74480

CVE.ORG link : CVE-2026-74480

JSON object : View

Products Affected

No product.

CWE

No CWE.

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After br_multicast_del_pg() removes p,\ncontinuing the loop advances pp through the deleted entry.\n\nIf multicast-to-unicast was enabled, the bridge can hold multiple port\ngroups for the same port and group with different source MAC\naddresses. Once multicast-to-unicast is disabled,\nbr_port_group_equal() matches those entries by port only. A fast leave\ncan then delete one entry and continue from its stale next pointer,\nleaving mp->ports pointing at a deleted port group.\n\nFast leave only needs to remove one matching port group. Break after\nbr_multicast_del_pg() so the loop stops before dereferencing the\nremoved entry."}], "lastModified": "2026-08-19T17:21:05.127", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}