GHSA-92HV-JCVF-RQG6

Vulnerability from github – Published: 2026-05-28 12:30 – Updated: 2026-10-15 03:36
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

ip6_gre: Use cached t->net in ip6erspan_changelink().

After commit 5e72ce3e3980 ("net: ipv6: Use link netns in newlink() of rtnl_link_ops"), ip6erspan_newlink() correctly resolves the per-netns ip6gre hash via link_net. ip6erspan_changelink() was not converted in that series and still uses dev_net(dev), which diverges from the device's creation netns after IFLA_NET_NS_FD migration.

This re-inserts the tunnel into the wrong per-netns hash. The original netns keeps a stale entry. When that netns is later destroyed, ip6gre_exit_rtnl_net() walks the stale entry, producing a slab-use-after-free reported by KASAN, followed by a kernel BUG at net/core/dev.c (LIST_POISON1) in unregister_netdevice_many_notify().

Reachable from an unprivileged user namespace (unshare --user --map-root-user --net).

ip6gre_changelink() earlier in the same file already uses the cached t->net; only ip6erspan_changelink() has the wrong shape.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-46120"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-28T10:16:27Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_gre: Use cached t-\u003enet in ip6erspan_changelink().\n\nAfter commit 5e72ce3e3980 (\"net: ipv6: Use link netns in newlink() of\nrtnl_link_ops\"), ip6erspan_newlink() correctly resolves the per-netns\nip6gre hash via link_net. ip6erspan_changelink() was not converted in\nthat series and still uses dev_net(dev), which diverges from the\ndevice\u0027s creation netns after IFLA_NET_NS_FD migration.\n\nThis re-inserts the tunnel into the wrong per-netns hash. The\noriginal netns keeps a stale entry. When that netns is later\ndestroyed, ip6gre_exit_rtnl_net() walks the stale entry, producing a\nslab-use-after-free reported by KASAN, followed by a kernel BUG at\nnet/core/dev.c (LIST_POISON1) in unregister_netdevice_many_notify().\n\nReachable from an unprivileged user namespace (unshare --user\n--map-root-user --net).\n\nip6gre_changelink() earlier in the same file already uses the cached\nt-\u003enet; only ip6erspan_changelink() has the wrong shape.",
  "id": "GHSA-92hv-jcvf-rqg6",
  "modified": "2026-10-15T03:36:00Z",
  "published": "2026-05-28T12:30:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46120"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-784472.html"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/01b71ff2857d3598337de11e7840a8e3ff21553c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0fcf6731706f73494245a9c0d64f93bebf95bb51"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1d324c2f43f70c965f25c58cc3611c779adbe47e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/311fdd26eb4443d43b909cc67a10f3a5fd1b21b2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7bd0f2b162b426b343a114e1b329f0d8d14fdc6e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cf7fc624329e76c6394653d12353e1d033adea91"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e70cfb40c3a99b232cd42c6a6a10f0d8e039dc82"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/eca62bb0569de4d43a4dac06a2092a9d4ca1d702"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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