xen-netback: reject zero-queue configuration from guest

{
  "id": "35167b6d5979f4f552532cf5dea095022ca952e1a81a4f5d65974dd0a2dc0a15",
  "url": "https://osv.dev/vulnerability/CVE-2026-45890",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "xen-netback: reject zero-queue configuration from guest",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: xen-netback: reject zero-queue configuration from guest A malicious or buggy Xen guest can write \"0\" to the xenbus key \"multi-queue-num-queues\". The connect() function in the backend only validates the upper bound (requested_num_queues > xenvif_max_queues) but not zero, allowing requested_num_queues=0 to reach vzalloc(array_size(0, sizeof(struct xenvif_queue))), which triggers WARN_ON_ONCE(!size) in __vmalloc_node_range(). On systems with panic_on_warn=1, this allows a guest-to-host denial of service. The Xen network interface specification requires the queue count to be \"greater than zero\". Add a zero check to match the validation already present in xen-blkback, which has included this guard since its multi-queue support was added.",
    "evidence": "osv:CVE-2026-45890",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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        "affected_versions": []
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    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-45890",
      "aliases": [
        "CVE-2026-45890"
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      "affected": [
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            "ecosystem": "Linux"
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      ],
      "modified": "2026-10-28T02:30:34.919150697Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2993e0f904c45f8af12917344bb1cac7ccd05a60",
        "https://git.kernel.org/stable/c/654780dee9eae419e1648ea58462c4efe54518fa",
        "https://git.kernel.org/stable/c/6d1dc8014334c7fb25719999bca84d811e60a559",
        "https://git.kernel.org/stable/c/787bfa423228c4b02ba3368128f625d579085353",
        "https://git.kernel.org/stable/c/88b0fced1bbbfdb356a007592604008ffc93a6a1",
        "https://git.kernel.org/stable/c/ce66d6786de45b7ed9cbbdc0988054bf09e58f54",
        "https://git.kernel.org/stable/c/d99f69ddc70fd9f4b8148add62209a1a8eb5c615",
        "https://git.kernel.org/stable/c/ec4859ac5c933e3315543a61adc1ca4358006a41",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45890.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-45890",
        "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/2026/45xxx/CVE-2026-45890.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-45890",
        "evidence": "/id"
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    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 502217,
  "published_at": "2026-05-27T12:17:01.466+00:00"
}