{"id":"CVE-2026-99117","summary":"net: bridge: mcast: don't truncate the port group walk on teardown","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: mcast: don't truncate the port group walk on teardown\n\n__br_multicast_disable_port_ctx() and br_multicast_del_port() walk\nport-\u003emglist with hlist_for_each_entry_safe(). However,\nbr_multicast_find_del_pg() can also delete other entries from the same\nlist through br_multicast_fwd_src_remove() or __fwd_del_star_excl().\n\nIf such an entry is the iterator's saved next node, hlist_del_init()\nclears its -\u003enext and terminates the walk early. The reproducer triggers\nthis in both teardown walks, leaving port groups in the bridge mdb with\na dangling -\u003ekey.port after del_nbp() frees the port:\n\n  BUG: KASAN: slab-use-after-free in __mdb_fill_info+0x1191/0x1320\n   __mdb_fill_info+0x1191/0x1320\n   br_mdb_dump+0x594/0xe40\n   rtnl_mdb_dump+0x1cf/0x5d0\n\nUse hlist_del_init_rcu() to unlink the group while preserving -\u003enext.\nbr_multicast_del_pg() and the teardown walks run under\nbr-\u003emulticast_lock. The GC worker must acquire the same lock before\ndetaching the group for destruction, so the node remains alive while\nthe walk uses the preserved pointer.\n\nPreserving -\u003enext means a walk can now reach a group that an earlier\niteration already deleted as a side effect. That group is off mp-\u003eports,\nso br_multicast_find_del_pg() would fall through its port scan and hit\nthe trailing WARN_ON(1). Skip such groups at the top of that helper: a\nport group is put on port-\u003emglist when it is created and only unlinked\nwhen it is deleted, so hlist_unhashed() identifies exactly this case.","modified":"2026-11-02T02:30:44.742653874Z","published":"2026-10-28T10:34:33.874Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99117.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5a3f7a683aee56e1f15c9d53041f3236767eaae7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8243d587a081e790ad96e80d48eef44d9f7ef005"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ab836d56ff43f2e7927e88c83cd02c47a98a672e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b0db9f4ff402becff710ab27dbd9f6fe4850b47e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b45e8c24608c992d1e2cea047eb5bcbfa537f86b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/be331b23c650de9518f8266b901d8abb9b36af77"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e69d4927dacd6ddaff09777a89efc0d3143d3b0d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99117.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99117"},{"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":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2"},{"fixed":"be331b23c650de9518f8266b901d8abb9b36af77"},{"fixed":"ab836d56ff43f2e7927e88c83cd02c47a98a672e"},{"fixed":"025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8"},{"fixed":"b0db9f4ff402becff710ab27dbd9f6fe4850b47e"},{"fixed":"e69d4927dacd6ddaff09777a89efc0d3143d3b0d"},{"fixed":"8243d587a081e790ad96e80d48eef44d9f7ef005"},{"fixed":"b45e8c24608c992d1e2cea047eb5bcbfa537f86b"},{"fixed":"5a3f7a683aee56e1f15c9d53041f3236767eaae7"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-99117.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.10.0"},{"fixed":"5.10.273"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.224"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.191"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.161"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.115"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.59"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.13"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-99117.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}