CVE-2026-98596 (GCVE-0-2026-98596)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:19 – Updated: 2026-10-19 09:22
VLAI
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.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7018 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 98aa546af5e4f180439c82da403cc77926d3953b , < 5045aa25f3790dcdb158a58ac60ccf8da42959aa (git)
Affected: 98aa546af5e4f180439c82da403cc77926d3953b , < ed902d5546fb9c142b3216d8eec914fa1bc0aa80 (git)
Affected: 98aa546af5e4f180439c82da403cc77926d3953b , < f9722746df13a8a29103c847ef56b02c11ce0963 (git)
Affected: 98aa546af5e4f180439c82da403cc77926d3953b , < be31fe6333f534155e6b408f1ef6d77974bb41aa (git)
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Linux Linux Affected: 6.11
Unaffected: 0 , < 6.11 (semver)
Unaffected: 6.12.112 , ≤ 6.12.* (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "include/net/ip6_route.h",
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: Fix dst leak for uncached routes.\n\nip6_route_output_flags(), ip6_rt_put_flags(), and ip6_dst_check()\ndetect an uncached route by list_empty(\u0026rt-\u003edst.rt_uncached),\nwhich replaced the static DST_NOCACHE flag check in commit\na4c2fd7f7891 (\"net: remove DST_NOCACHE flag\").\n\nWhen a device is unregistered, rt6_uncached_list_flush_dev()\nunlinks uncached routes tied to the device from rt6_uncached_list.\n\nPreviously, they were moved to another list with list_move()\n(__list_del_entry() + list_add()), and since commit 98aa546af5e4\n(\"inet: remove (struct uncached_list)-\u003equarantine\"), the routes\nare just unlinked with list_del_init().\n\nIf list_del_init() runs concurrently, list_empty() evaluates to\ntrue; ip6_route_output_flags() calls dst_hold_safe() incorrectly\nand ip6_rt_put_flags() skips ip6_rt_put(), leaking dst, and thus\ndev tied via rt-\u003efrom as well.\n\nThe same race is partially fixed by commit 9a6f0c4d5796 (\"dst:\nfix races in rt6_uncached_list_del() and rt_del_uncached_list()\").\n\nLet\u0027s check rt6-\u003edst.rt_uncached_list instead.\n\nNote that IPv4 does not have the same issue."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:22:21.750Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/be31fe6333f534155e6b408f1ef6d77974bb41aa"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98596",
    "datePublished": "2026-10-18T15:19:09.189Z",
    "dateReserved": "2026-09-25T10:25:14.359Z",
    "dateUpdated": "2026-10-19T09:22:21.750Z",
    "state": "PUBLISHED"
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: Fix dst leak for uncached routes.\n\nip6_route_output_flags(), ip6_rt_put_flags(), and ip6_dst_check()\ndetect an uncached route by list_empty(\u0026rt-\u003edst.rt_uncached),\nwhich replaced the static DST_NOCACHE flag check in commit\na4c2fd7f7891 (\"net: remove DST_NOCACHE flag\").\n\nWhen a device is unregistered, rt6_uncached_list_flush_dev()\nunlinks uncached routes tied to the device from rt6_uncached_list.\n\nPreviously, they were moved to another list with list_move()\n(__list_del_entry() + list_add()), and since commit 98aa546af5e4\n(\"inet: remove (struct uncached_list)-\u003equarantine\"), the routes\nare just unlinked with list_del_init().\n\nIf list_del_init() runs concurrently, list_empty() evaluates to\ntrue; ip6_route_output_flags() calls dst_hold_safe() incorrectly\nand ip6_rt_put_flags() skips ip6_rt_put(), leaking dst, and thus\ndev tied via rt-\u003efrom as well.\n\nThe same race is partially fixed by commit 9a6f0c4d5796 (\"dst:\nfix races in rt6_uncached_list_del() and rt_del_uncached_list()\").\n\nLet\u0027s check rt6-\u003edst.rt_uncached_list instead.\n\nNote that IPv4 does not have the same issue."
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        "metrics": {},
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      "cve": "CVE-2026-98596",
      "id": "CVE-2026-98596",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_affected": "91",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ipv6: Fix dst leak for uncached routes",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98596.json",
      "version": "3"
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  }
}



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