{"id":"CVE-2026-64032","summary":"bridge: mcast: Fix a possible use-after-free when removing a bridge port","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbridge: mcast: Fix a possible use-after-free when removing a bridge port\n\nWhen per-VLAN multicast snooping is enabled, the bridge iterates over\nall the bridge ports, disables the per-port multicast context on each\nport and enables the per-{port, VLAN} multicast contexts instead. The\nreverse happens when per-VLAN multicast snooping is disabled.\n\nWhen global multicast snooping is enabled, the bridge iterates over all\nthe bridge ports and enables the per-port multicast context on each\nport. The reverse happens when multicast snooping is disabled.\n\nThe above scheme can result in a situation where both types of contexts\n(per-port and per-{port, VLAN}) are enabled on a single bridge port:\n\n # ip link add name br1 up type bridge mcast_snooping 1 mcast_querier 1 vlan_filtering 1\n # ip link add name dummy1 up master br1 type dummy\n # ip link set dev br1 type bridge mcast_vlan_snooping 1\n # ip link set dev br1 type bridge mcast_snooping 0\n # ip link set dev br1 type bridge mcast_snooping 1\n\nThis is not intended and it is a problem since the commit cited below.\nPrior to this commit, when removing a bridge port,\nbr_multicast_disable_port() would disable the per-port multicast context\nand the per-{port, VLAN} multicast contexts would get disabled when\nflushing VLANs.\n\nAfter this commit, br_multicast_disable_port() only disables the\nper-port multicast context if per-VLAN multicast snooping is disabled.\nIf both types of contexts were enabled on the port when it was removed,\nthe per-port multicast context would remain enabled when freeing the\nbridge port, leading to a use-after-free [1].\n\nFix by preventing the bridge from enabling / disabling the per-port\nmulticast contexts when toggling global multicast snooping if per-VLAN\nmulticast snooping is enabled.\n\n[1]\nODEBUG: free active (active state 0) object: ffff88810f8bda78 object type: timer_list hint: br_ip6_multicast_port_query_expired (net/bridge/br_multicast.c:1927)\nWARNING: lib/debugobjects.c:629 at debug_print_object+0x1b1/0x3e0, CPU#5: swapper/5/0\n[...]\nCall Trace:\n\u003cIRQ\u003e\n__debug_check_no_obj_freed (lib/debugobjects.c:1116)\nkfree (mm/slub.c:2620 mm/slub.c:6250 mm/slub.c:6565)\nkobject_cleanup (lib/kobject.c:689)\nrcu_do_batch (kernel/rcu/tree.c:2617)\nrcu_core (kernel/rcu/tree.c:2869)\nhandle_softirqs (kernel/softirq.c:622)\n__irq_exit_rcu (kernel/softirq.c:656 kernel/softirq.c:496 kernel/softirq.c:735)\nirq_exit_rcu (kernel/softirq.c:752)\nsysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1061 (discriminator 47) arch/x86/kernel/apic/apic.c:1061 (discriminator 47))\n\u003c/IRQ\u003e","modified":"2026-10-28T02:31:13.184434704Z","published":"2026-07-19T15:39:22.228Z","related":["ALSA-2026:83207","ALSA-2026:86033"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64032.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1900ca8acb92fbea8bf9abef9927c7fed03db7fc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4df78ff02629c7729168f0696a7a2123c389818d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7213256c91ed778a0997c2029c152b18dc50e4fd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a9224862d597d0eed0a34bbb27343f703fc4113f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ddefd1b8e5eb58933a697ab38334f0fd82e7fb8b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ebe5561154c823b323bd06e350b55e0b8604d851"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ed3b69e60385a03df11c6d12e5d7bdf0f4a11b70"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64032.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64032"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"410a033bfa8c7daefbae0225c836693db2149ec1"},{"fixed":"ddefd1b8e5eb58933a697ab38334f0fd82e7fb8b"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c6d16eab122744df698f18b47cf771945cd55066"},{"fixed":"ed3b69e60385a03df11c6d12e5d7bdf0f4a11b70"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"b4c83b37490d61cfdd62a2b29e98a9b89004b5c0"},{"fixed":"1900ca8acb92fbea8bf9abef9927c7fed03db7fc"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"78f768e36c065ca3f88272fcf39014782c2d4ecd"},{"fixed":"ebe5561154c823b323bd06e350b55e0b8604d851"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"4b30ae9adb047dd0a7982975ec3933c529537026"},{"fixed":"a9224862d597d0eed0a34bbb27343f703fc4113f"},{"fixed":"7213256c91ed778a0997c2029c152b18dc50e4fd"},{"fixed":"4df78ff02629c7729168f0696a7a2123c389818d"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5.15.186"},{"fixed":"5.15.209"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.1.142"},{"fixed":"6.1.175"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.6.95"},{"fixed":"6.6.142"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.12.35"},{"fixed":"6.12.92"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.15.4"},{"fixed":"6.16"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c996e25df0b3282c724bb5aca434518bc08cd963"}]}],"versions":["v5.15.208","v5.15.207","v5.15.206","v5.15.205","v5.15.204","v5.15.203","v5.15.202","v5.15.201","v5.15.200","v5.15.199","v5.15.198","v5.15.197","v5.15.196","v5.15.195","v5.15.194","v5.15.193","v5.15.192","v5.15.191","v5.15.190","v5.15.189","v5.15.188","v5.15.187","v5.15.186","v6.1.174","v6.1.173","v6.1.172","v6.1.171","v6.1.170","v6.1.169","v6.1.168","v6.1.167","v6.1.166","v6.1.165","v6.1.164","v6.1.163","v6.1.162","v6.1.161","v6.1.160","v6.1.159","v6.1.158","v6.1.157","v6.1.156","v6.1.155","v6.1.154","v6.1.153","v6.1.152","v6.1.151","v6.1.150","v6.1.149","v6.1.148","v6.1.147","v6.1.146","v6.1.145","v6.1.144","v6.1.143","v6.1.142","v6.6.141","v6.6.140","v6.6.139","v6.6.138","v6.6.137","v6.6.136","v6.6.135","v6.6.134","v6.6.133","v6.6.132","v6.6.131","v6.6.130","v6.6.129","v6.6.128","v6.6.127","v6.6.126","v6.6.125","v6.6.124","v6.6.123","v6.6.122","v6.6.121","v6.6.120","v6.6.119","v6.6.118","v6.6.117","v6.6.116","v6.6.115","v6.6.114","v6.6.113","v6.6.112","v6.6.111","v6.6.110","v6.6.109","v6.6.108","v6.6.107","v6.6.106","v6.6.105","v6.6.104","v6.6.103","v6.6.102","v6.6.101","v6.6.100","v6.6.99","v6.6.98","v6.6.97","v6.6.96","v6.6.95","v6.12.91","v6.12.90","v6.12.89","v6.12.88","v6.12.87","v6.12.86","v6.12.85","v6.12.84","v6.12.83","v6.12.82","v6.12.81","v6.12.80","v6.12.79","v6.12.78","v6.12.77","v6.12.76","v6.12.75","v6.12.74","v6.12.73","v6.12.72","v6.12.71","v6.12.70","v6.12.69","v6.12.68","v6.12.67","v6.12.66","v6.12.65","v6.12.64","v6.12.63","v6.12.62","v6.12.61","v6.12.60","v6.12.59","v6.12.58","v6.12.57","v6.12.56","v6.12.55","v6.12.54","v6.12.53","v6.12.52","v6.12.51","v6.12.50","v6.12.49","v6.12.48","v6.12.47"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