{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels\n\nseg6_input_core() and rpl_input() call ip6_route_input() which sets a\nNOREF dst on the skb, then pass it to dst_cache_set_ip6() invoking\ndst_hold() unconditionally.\nOn PREEMPT_RT, ksoftirqd is preemptible and a higher-priority task can\nrelease the underlying pcpu_rt between the lookup and the caching\nthrough a concurrent FIB lookup on a shared nexthop.\nSimplified race sequence:\n\n  ksoftirqd/X                       higher-prio task (same CPU X)\n  -----------                       --------------------------------\n  seg6_input_core(,skb)/rpl_input(skb)\n    dst_cache_get()\n      -\u003e miss\n    ip6_route_input(skb)\n      -\u003e ip6_pol_route(,skb,flags)\n         [RT6_LOOKUP_F_DST_NOREF in flags]\n        -\u003e FIB lookup resolves fib6_nh\n           [nhid=N route]\n        -\u003e rt6_make_pcpu_route()\n           [creates pcpu_rt, refcount=1]\n             pcpu_rt-\u003esernum = fib6_sernum\n             [fib6_sernum=W]\n           -\u003e cmpxchg(fib6_nh.rt6i_pcpu,\n                      NULL, pcpu_rt)\n              [slot was empty, store succeeds]\n      -\u003e skb_dst_set_noref(skb, dst)\n         [dst is pcpu_rt, refcount still 1]\n\n                                    rt_genid_bump_ipv6()\n                                      -\u003e bumps fib6_sernum\n                                         [fib6_sernum from W to Z]\n                                    ip6_route_output()\n                                      -\u003e ip6_pol_route()\n                                        -\u003e FIB lookup resolves fib6_nh\n                                           [nhid=N]\n                                        -\u003e rt6_get_pcpu_route()\n                                             pcpu_rt-\u003esernum != fib6_sernum\n                                             [W \u003c\u003e Z, stale]\n                                          -\u003e prev = xchg(rt6i_pcpu, NULL)\n                                          -\u003e dst_release(prev)\n                                             [prev is pcpu_rt,\n                                              refcount 1-\u003e0, dead]\n\n    dst = skb_dst(skb)\n    [dst is the dead pcpu_rt]\n    dst_cache_set_ip6(dst)\n      -\u003e dst_hold() on dead dst\n      -\u003e WARN / use-after-free\n\nFor the race to occur, ksoftirqd must be preemptible (PREEMPT_RT without\nPREEMPT_RT_NEEDS_BH_LOCK) and a concurrent task must be able to release\nthe pcpu_rt. Shared nexthop objects provide such a path, as two routes\npointing to the same nhid share the same fib6_nh and its rt6i_pcpu\nentry.\n\nFix seg6_input_core() and rpl_input() by calling skb_dst_force() after\nip6_route_input() to force the NOREF dst into a refcounted one before\ncaching.\nThe output path is not affected as ip6_route_output() already returns a\nrefcounted dst."
    }
  ],
  "id": "CVE-2026-46099",
  "lastModified": "2026-05-27T14:48:03.013",
  "metrics": {},
  "published": "2026-05-27T14:17:31.557",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/52f9db67f8f35f436366cf4980b4f0a2583d0ef0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6bd17925bd6866027a6555db17905b9fc073d38d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9dd5481f960e337b81d7dfe429529495c1c481c0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b778b6d095421619c331fd2d7751143cd5387103"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-46099"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-27T14:17:31Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels\n\nseg6_input_core() and rpl_input() call ip6_route_input() which sets a\nNOREF dst on the skb, then pass it to dst_cache_set_ip6() invoking\ndst_hold() unconditionally.\nOn PREEMPT_RT, ksoftirqd is preemptible and a higher-priority task can\nrelease the underlying pcpu_rt between the lookup and the caching\nthrough a concurrent FIB lookup on a shared nexthop.\nSimplified race sequence:\n\n  ksoftirqd/X                       higher-prio task (same CPU X)\n  -----------                       --------------------------------\n  seg6_input_core(,skb)/rpl_input(skb)\n    dst_cache_get()\n      -\u003e miss\n    ip6_route_input(skb)\n      -\u003e ip6_pol_route(,skb,flags)\n         [RT6_LOOKUP_F_DST_NOREF in flags]\n        -\u003e FIB lookup resolves fib6_nh\n           [nhid=N route]\n        -\u003e rt6_make_pcpu_route()\n           [creates pcpu_rt, refcount=1]\n             pcpu_rt-\u003esernum = fib6_sernum\n             [fib6_sernum=W]\n           -\u003e cmpxchg(fib6_nh.rt6i_pcpu,\n                      NULL, pcpu_rt)\n              [slot was empty, store succeeds]\n      -\u003e skb_dst_set_noref(skb, dst)\n         [dst is pcpu_rt, refcount still 1]\n\n                                    rt_genid_bump_ipv6()\n                                      -\u003e bumps fib6_sernum\n                                         [fib6_sernum from W to Z]\n                                    ip6_route_output()\n                                      -\u003e ip6_pol_route()\n                                        -\u003e FIB lookup resolves fib6_nh\n                                           [nhid=N]\n                                        -\u003e rt6_get_pcpu_route()\n                                             pcpu_rt-\u003esernum != fib6_sernum\n                                             [W \u003c\u003e Z, stale]\n                                          -\u003e prev = xchg(rt6i_pcpu, NULL)\n                                          -\u003e dst_release(prev)\n                                             [prev is pcpu_rt,\n                                              refcount 1-\u003e0, dead]\n\n    dst = skb_dst(skb)\n    [dst is the dead pcpu_rt]\n    dst_cache_set_ip6(dst)\n      -\u003e dst_hold() on dead dst\n      -\u003e WARN / use-after-free\n\nFor the race to occur, ksoftirqd must be preemptible (PREEMPT_RT without\nPREEMPT_RT_NEEDS_BH_LOCK) and a concurrent task must be able to release\nthe pcpu_rt. Shared nexthop objects provide such a path, as two routes\npointing to the same nhid share the same fib6_nh and its rt6i_pcpu\nentry.\n\nFix seg6_input_core() and rpl_input() by calling skb_dst_force() after\nip6_route_input() to force the NOREF dst into a refcounted one before\ncaching.\nThe output path is not affected as ip6_route_output() already returns a\nrefcounted dst.",
  "id": "GHSA-9x88-7c3c-r34g",
  "modified": "2026-05-27T15:33:24Z",
  "published": "2026-05-27T15:33:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46099"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/52f9db67f8f35f436366cf4980b4f0a2583d0ef0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6bd17925bd6866027a6555db17905b9fc073d38d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9dd5481f960e337b81d7dfe429529495c1c481c0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b778b6d095421619c331fd2d7751143cd5387103"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

{
  "document": {
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Public",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2026-46099 net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-46099.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels",
    "tracking": {
      "current_release_date": "2026-05-29T01:40:16.000Z",
      "generator": {
        "date": "2026-05-29T07:23:45.829Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2026-46099",
      "initial_release_date": "2026-05-02T00:00:00.000Z",
      "revision_history": [
        {
          "date": "2026-05-28T01:10:13.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        },
        {
          "date": "2026-05-28T14:41:18.000Z",
          "legacy_version": "1.1",
          "number": "2",
          "summary": "Information published."
        },
        {
          "date": "2026-05-29T01:40:16.000Z",
          "legacy_version": "2",
          "number": "3",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "3"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "3.0",
                "product": {
                  "name": "Azure Linux 3.0",
                  "product_id": "17084"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "azl3 kernel 0:6.6.139.1-1.azl3",
                "product": {
                  "name": "azl3 kernel 0:6.6.139.1-1.azl3",
                  "product_id": "1"
                }
              }
            ],
            "category": "product_name",
            "name": "kernel"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 kernel 0:6.6.139.1-1.azl3 as a component of Azure Linux 3.0",
          "product_id": "17084-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "17084"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-46099",
      "notes": [
        {
          "category": "general",
          "text": "Linux",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "known_affected": [
          "17084-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-46099 net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-46099.json"
        }
      ],
      "remediations": [
        {
          "category": "none_available",
          "date": "2026-05-28T01:10:13.000Z",
          "details": "There is no fix available for this vulnerability as of now",
          "product_ids": [
            "17084-1"
          ]
        }
      ],
      "title": "net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels"
    }
  ]
}