{"id":"CVE-2026-99117","aliases":[],"title":"net: bridge: mcast: don't truncate the port group walk on teardown","titleSource":"Linux","descriptionSource":"Linux","products":[{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"8243d587a081e790ad96e80d48eef44d9f7ef005","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"b45e8c24608c992d1e2cea047eb5bcbfa537f86b","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"5a3f7a683aee56e1f15c9d53041f3236767eaae7","versionType":"git"}],"defaultStatus":"unaffected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99117"},{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"5.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.10","versionType":"semver"},{"version":"6.18.59","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"defaultStatus":"affected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99117"}],"remediation":[],"description":"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->mglist 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 ->next and terminates the walk early. The reproducer triggers\nthis in both teardown walks, leaving port groups in the bridge mdb with\na dangling ->key.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 ->next.\nbr_multicast_del_pg() and the teardown walks run under\nbr->multicast_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 ->next means a walk can now reach a group that an earlier\niteration already deleted as a side effect. That group is off mp->ports,\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->mglist when it is created and only unlinked\nwhen it is deleted, so hlist_unhashed() identifies exactly this case.","severity":"unknown","score":null,"published":"2026-10-28T10:34:33.874Z","modified":"2026-10-28T10:34:33.874Z","withdrawn":false,"knownExploited":false,"affected":[],"references":["https://git.kernel.org/stable/c/8243d587a081e790ad96e80d48eef44d9f7ef005","https://git.kernel.org/stable/c/b45e8c24608c992d1e2cea047eb5bcbfa537f86b","https://git.kernel.org/stable/c/5a3f7a683aee56e1f15c9d53041f3236767eaae7"],"sources":[{"name":"CVE","id":"CVE-2026-99117","modified":"2026-10-28T10:34:33.874Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-99117"}],"assessments":[],"sourceAffected":[],"kev":{"status":"not-listed","checkedAt":"2026-10-28T20:45:31.448Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}