ipv6: Fix dst leak for uncached routes.

{
  "id": "efc2660efccf0ef664e3144772153c35243bbf9d1edd3c2be6bd3f936337b6e5",
  "url": "https://osv.dev/vulnerability/CVE-2026-98596",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ipv6: Fix dst leak for uncached routes.",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix dst leak for uncached routes. ip6_route_output_flags(), ip6_rt_put_flags(), and ip6_dst_check() detect an uncached route by list_empty(&rt->dst.rt_uncached), which replaced the static DST_NOCACHE flag check in commit a4c2fd7f7891 (\"net: remove DST_NOCACHE flag\"). When a device is unregistered, rt6_uncached_list_flush_dev() unlinks uncached routes tied to the device from rt6_uncached_list. Previously, they were moved to another list with list_move() (__list_del_entry() + list_add()), and since commit 98aa546af5e4 (\"inet: remove (struct uncached_list)->quarantine\"), the routes are just unlinked with list_del_init(). If list_del_init() runs concurrently, list_empty() evaluates to true; ip6_route_output_flags() calls dst_hold_safe() incorrectly and ip6_rt_put_flags() skips ip6_rt_put(), leaking dst, and thus dev tied via rt->from as well. The same race is partially fixed by commit 9a6f0c4d5796 (\"dst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()\"). Let's check rt6->dst.rt_uncached_list instead. Note that IPv4 does not have the same issue.",
    "evidence": "osv:CVE-2026-98596",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.112",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.55",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98596",
      "aliases": [
        "CVE-2026-98596"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "fixed": "ed902d5546fb9c142b3216d8eec914fa1bc0aa80"
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                {
                  "fixed": "f9722746df13a8a29103c847ef56b02c11ce0963"
                },
                {
                  "fixed": "be31fe6333f534155e6b408f1ef6d77974bb41aa"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98596.json"
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        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.11.0"
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              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.13.0"
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                {
                  "fixed": "6.18.55"
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            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
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                {
                  "fixed": "7.2.9"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98596.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:38.306646300Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/5045aa25f3790dcdb158a58ac60ccf8da42959aa",
        "https://git.kernel.org/stable/c/be31fe6333f534155e6b408f1ef6d77974bb41aa",
        "https://git.kernel.org/stable/c/ed902d5546fb9c142b3216d8eec914fa1bc0aa80",
        "https://git.kernel.org/stable/c/f9722746df13a8a29103c847ef56b02c11ce0963",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98596.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98596",
        "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/2026/98xxx/CVE-2026-98596.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98596",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 505817,
  "published_at": "2026-10-18T15:19:09.189+00:00"
}