{"id":"CVE-2026-99117","state":"PUBLISHED","title":"net: bridge: mcast: don't truncate the port group walk on teardown","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.","publishedAt":"2026-10-28T10:34:33.874Z","updatedAt":"2026-10-30T12:41:54.603Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"be331b23c650de9518f8266b901d8abb9b36af77","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"ab836d56ff43f2e7927e88c83cd02c47a98a672e","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"b0db9f4ff402becff710ab27dbd9f6fe4850b47e","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"e69d4927dacd6ddaff09777a89efc0d3143d3b0d","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"8243d587a081e790ad96e80d48eef44d9f7ef005","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"b45e8c24608c992d1e2cea047eb5bcbfa537f86b","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"5a3f7a683aee56e1f15c9d53041f3236767eaae7","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_multicast.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.10","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.161","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.115","status":"unaffected","lessThanOrEqual":"6.12.*","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"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_multicast.c"]}],"references":["https://git.kernel.org/stable/c/be331b23c650de9518f8266b901d8abb9b36af77","https://git.kernel.org/stable/c/ab836d56ff43f2e7927e88c83cd02c47a98a672e","https://git.kernel.org/stable/c/025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8","https://git.kernel.org/stable/c/b0db9f4ff402becff710ab27dbd9f6fe4850b47e","https://git.kernel.org/stable/c/e69d4927dacd6ddaff09777a89efc0d3143d3b0d","https://git.kernel.org/stable/c/8243d587a081e790ad96e80d48eef44d9f7ef005","https://git.kernel.org/stable/c/b45e8c24608c992d1e2cea047eb5bcbfa537f86b","https://git.kernel.org/stable/c/5a3f7a683aee56e1f15c9d53041f3236767eaae7"],"weaknesses":[],"ingestedAt":"2026-10-30T13:02:04.640Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99117.json","commit":"cb14bf1b43b0c9f05f7f40eae2246263fd430780","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99117","state":"PUBLISHED","datePublished":"2026-10-28T10:34:33.874Z","dateUpdated":"2026-10-30T12:41:54.603Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.392Z"},"containers":{"cna":{"title":"net: bridge: mcast: don't truncate the port group walk on teardown","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"be331b23c650de9518f8266b901d8abb9b36af77","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"ab836d56ff43f2e7927e88c83cd02c47a98a672e","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"b0db9f4ff402becff710ab27dbd9f6fe4850b47e","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"e69d4927dacd6ddaff09777a89efc0d3143d3b0d","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"8243d587a081e790ad96e80d48eef44d9f7ef005","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"b45e8c24608c992d1e2cea047eb5bcbfa537f86b","versionType":"git"},{"version":"b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2","status":"affected","lessThan":"5a3f7a683aee56e1f15c9d53041f3236767eaae7","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_multicast.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.10","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.161","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.115","status":"unaffected","lessThanOrEqual":"6.12.*","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"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_multicast.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/be331b23c650de9518f8266b901d8abb9b36af77"},{"url":"https://git.kernel.org/stable/c/ab836d56ff43f2e7927e88c83cd02c47a98a672e"},{"url":"https://git.kernel.org/stable/c/025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8"},{"url":"https://git.kernel.org/stable/c/b0db9f4ff402becff710ab27dbd9f6fe4850b47e"},{"url":"https://git.kernel.org/stable/c/e69d4927dacd6ddaff09777a89efc0d3143d3b0d"},{"url":"https://git.kernel.org/stable/c/8243d587a081e790ad96e80d48eef44d9f7ef005"},{"url":"https://git.kernel.org/stable/c/b45e8c24608c992d1e2cea047eb5bcbfa537f86b"},{"url":"https://git.kernel.org/stable/c/5a3f7a683aee56e1f15c9d53041f3236767eaae7"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:41:54.603Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.6.161"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.12.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.18.59"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"7.2.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}