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CVE-2026-43100

Estado: AnalizadaMedia (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

bridge: guard local VLAN-0 FDB helpers against NULL vlan group

When CONFIG_BRIDGE_VLAN_FILTERING is not set, br_vlan_group() and nbp_vlan_group() return NULL (br_private.h stub definitions). The BR_BOOLOPT_FDB_LOCAL_VLAN_0 toggle code is compiled unconditionally and reaches br_fdb_delete_locals_per_vlan_port() and br_fdb_insert_locals_per_vlan_port(), where the NULL vlan group pointer is dereferenced via list_for_each_entry(v, &vg->vlan_list, vlist).

The observed crash is in the delete path, triggered when creating a bridge with IFLA_BR_MULTI_BOOLOPT containing BR_BOOLOPT_FDB_LOCAL_VLAN_0 via RTM_NEWLINK. The insert helper has the same bug pattern.

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Add NULL checks for the vlan group pointer in both helpers, returning early when there are no VLANs to iterate. This matches the existing pattern used by other bridge FDB functions such as br_fdb_add() and br_fdb_delete().

Detalles técnicos trazas, registros y código del informe original
  Oops: general protection fault, probably for non-canonical address 0xdffffc0000000056: 0000 [#1] KASAN NOPTI
  KASAN: null-ptr-deref in range [0x00000000000002b0-0x00000000000002b7]
  RIP: 0010:br_fdb_delete_locals_per_vlan+0x2b9/0x310
  Call Trace:
   br_fdb_toggle_local_vlan_0+0x452/0x4c0
   br_toggle_fdb_local_vlan_0+0x31/0x80 net/bridge/br.c:276
   br_boolopt_toggle net/bridge/br.c:313
   br_boolopt_multi_toggle net/bridge/br.c:364
   br_changelink net/bridge/br_netlink.c:1542
   br_dev_newlink net/bridge/br_netlink.c:1575

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

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          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
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  "published": "2026-05-06T10:16:23.523",
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          "value": "CWE-476"
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      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbridge: guard local VLAN-0 FDB helpers against NULL vlan group\n\nWhen CONFIG_BRIDGE_VLAN_FILTERING is not set, br_vlan_group() and\nnbp_vlan_group() return NULL (br_private.h stub definitions). The\nBR_BOOLOPT_FDB_LOCAL_VLAN_0 toggle code is compiled unconditionally and\nreaches br_fdb_delete_locals_per_vlan_port() and\nbr_fdb_insert_locals_per_vlan_port(), where the NULL vlan group pointer\nis dereferenced via list_for_each_entry(v, &vg->vlan_list, vlist).\n\nThe observed crash is in the delete path, triggered when creating a\nbridge with IFLA_BR_MULTI_BOOLOPT containing BR_BOOLOPT_FDB_LOCAL_VLAN_0\nvia RTM_NEWLINK. The insert helper has the same bug pattern.\n\n  Oops: general protection fault, probably for non-canonical address 0xdffffc0000000056: 0000 [#1] KASAN NOPTI\n  KASAN: null-ptr-deref in range [0x00000000000002b0-0x00000000000002b7]\n  RIP: 0010:br_fdb_delete_locals_per_vlan+0x2b9/0x310\n  Call Trace:\n   br_fdb_toggle_local_vlan_0+0x452/0x4c0\n   br_toggle_fdb_local_vlan_0+0x31/0x80 net/bridge/br.c:276\n   br_boolopt_toggle net/bridge/br.c:313\n   br_boolopt_multi_toggle net/bridge/br.c:364\n   br_changelink net/bridge/br_netlink.c:1542\n   br_dev_newlink net/bridge/br_netlink.c:1575\n\nAdd NULL checks for the vlan group pointer in both helpers, returning\nearly when there are no VLANs to iterate. This matches the existing\npattern used by other bridge FDB functions such as br_fdb_add() and\nbr_fdb_delete()."
    }
  ],
  "lastModified": "2026-06-17T10:48:56.183",
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