net: bridge: stop fast-leave after deleting a port group

{
  "id": "022a78442e5bfb0ba2c0546f354eb6572e2fc71b36e607971e2c0b548c40ea5b",
  "url": "https://osv.dev/vulnerability/CVE-2026-74480",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net: bridge: stop fast-leave after deleting a port group",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net: bridge: stop fast-leave after deleting a port group br_multicast_leave_group() iterates mp->ports with pp = &p->next in its fast-leave path. After br_multicast_del_pg() removes p, continuing the loop advances pp through the deleted entry. If multicast-to-unicast was enabled, the bridge can hold multiple port groups for the same port and group with different source MAC addresses. Once multicast-to-unicast is disabled, br_port_group_equal() matches those entries by port only. A fast leave can then delete one entry and continue from its stale next pointer, leaving mp->ports pointing at a deleted port group. Fast leave only needs to remove one matching port group. Break after br_multicast_del_pg() so the loop stops before dereferencing the removed entry.",
    "evidence": "osv:CVE-2026-74480",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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    "severity": "critical",
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      "aliases": [
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      "metrics": [
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          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
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      "modified": "2026-10-28T02:30:41.295243973Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0309ebbc570000ea0df11c06b69798e5860c5f6f",
        "https://git.kernel.org/stable/c/159ad90cb929c033308bb39a2c5f8fbf393b77aa",
        "https://git.kernel.org/stable/c/1a109cc9890d017c41d77e6c82da739579c49f0b",
        "https://git.kernel.org/stable/c/4695430e8132420bf8de94da3eb36a6cf35fde6b",
        "https://git.kernel.org/stable/c/482bcb85139addb4e8ac8ed10baeda3e0aad4031",
        "https://git.kernel.org/stable/c/4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4",
        "https://git.kernel.org/stable/c/a39789f211b8a4125f0c70e05b30cf715f4f187d",
        "https://git.kernel.org/stable/c/d6c32e2e25a9a06ba021030e26b6d602a277eb72",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74480.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-74480",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74480.json"
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        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 509146,
  "published_at": "2026-08-15T12:27:13.803+00:00"
}