CVE-2026-99117

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: net: bridge: mcast: don't truncate the port group walk on teardown __br_multicast_disable_port_ctx() and br_multicast_del_port() walk port->mglist with hlist_for_each_entry_safe(). However, br_multicast_find_del_pg() can also delete other entries from the same list through br_multicast_fwd_src_remove() or __fwd_del_star_excl(). If such an entry is the iterator's saved next node, hlist_del_init() clears its ->next and terminates the walk early. The reproducer triggers this in both teardown walks, leaving port groups in the bridge mdb with a dangling ->key.port after del_nbp() frees the port: BUG: KASAN: slab-use-after-free in __mdb_fill_info+0x1191/0x1320 __mdb_fill_info+0x1191/0x1320 br_mdb_dump+0x594/0xe40 rtnl_mdb_dump+0x1cf/0x5d0 Use hlist_del_init_rcu() to unlink the group while preserving ->next. br_multicast_del_pg() and the teardown walks run under br->multicast_lock. The GC worker must acquire the same lock before detaching the group for destruction, so the node remains alive while the walk uses the preserved pointer. Preserving ->next means a walk can now reach a group that an earlier iteration already deleted as a side effect. That group is off mp->ports, so br_multicast_find_del_pg() would fall through its port scan and hit the trailing WARN_ON(1). Skip such groups at the top of that helper: a port group is put on port->mglist when it is created and only unlinked when it is deleted, so hlist_unhashed() identifies exactly this case.

Severity

Not scored

CVSS score

Not available

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-10-28 11:17:31.253000

Last modified

2026-10-30 13:21:46.133000

View original CVE JSON

{
  "id": "CVE-2026-99117",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-10-28T11:17:31.253",
  "lastModified": "2026-10-30T13:21:46.133",
  "vulnStatus": "Received",
  "cveTags": [],
  "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": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "net/bridge/br_multicast.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2",
              "lessThan": "be331b23c650de9518f8266b901d8abb9b36af77",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2",
              "lessThan": "ab836d56ff43f2e7927e88c83cd02c47a98a672e",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2",
              "lessThan": "025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2",
              "lessThan": "b0db9f4ff402becff710ab27dbd9f6fe4850b47e",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2",
              "lessThan": "e69d4927dacd6ddaff09777a89efc0d3143d3b0d",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2",
              "lessThan": "8243d587a081e790ad96e80d48eef44d9f7ef005",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2",
              "lessThan": "b45e8c24608c992d1e2cea047eb5bcbfa537f86b",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2",
              "lessThan": "5a3f7a683aee56e1f15c9d53041f3236767eaae7",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "net/bridge/br_multicast.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "5.10",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "5.10",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.10.273",
              "lessThanOrEqual": "5.10.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.15.224",
              "lessThanOrEqual": "5.15.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.191",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.161",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.115",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.59",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2.13",
              "lessThanOrEqual": "7.2.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.3",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5a3f7a683aee56e1f15c9d53041f3236767eaae7",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8243d587a081e790ad96e80d48eef44d9f7ef005",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ab836d56ff43f2e7927e88c83cd02c47a98a672e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b0db9f4ff402becff710ab27dbd9f6fe4850b47e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b45e8c24608c992d1e2cea047eb5bcbfa537f86b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/be331b23c650de9518f8266b901d8abb9b36af77",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/e69d4927dacd6ddaff09777a89efc0d3143d3b0d",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}