GHSA-225V-7W3R-PCQ9

Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-20 15:31
VLAI
Details

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

ip6: vti: Use ip6_tnl.net in vti6_changelink().

ip netns add ns1 ip netns add ns2 ip -n ns1 link add vti6_test type vti6 remote ::1 local ::2 key 7 ip -n ns1 link set vti6_test netns ns2 ip -n ns2 link set vti6_test type vti6 remote ::3 local ::4 key 9 ip netns del ns2 ip netns del ns1 [ 132.495484] ------------[ cut here ]------------ [ 132.497609] kernel BUG at net/core/dev.c:12376!

Commit 61220ab34948 ("vti6: Enable namespace changing") dropped NETIF_F_NETNS_LOCAL from vti6 devices. A vti6 tunnel can then move through IFLA_NET_NS_FD. After the move dev_net(dev) points at the new netns while t->net stays at the creation netns.

vti6_changelink() and vti6_update() still use dev_net(dev) and dev_net(t->dev). They unlink from one per netns hash and relink into another. The creation netns is left with a stale entry. cleanup_net() of that netns later walks freed memory.

Reachable from an unprivileged user namespace (unshare --user --map-root-user --net). Cross tenant scope on container hosts.

Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-63917"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T16:17:09Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6: vti: Use ip6_tnl.net in vti6_changelink().\n\nip netns add ns1\nip netns add ns2\nip -n ns1 link add vti6_test type vti6 remote ::1 local ::2 key 7\nip -n ns1 link set vti6_test netns ns2\nip -n ns2 link set vti6_test type vti6 remote ::3 local ::4 key 9\nip netns del ns2\nip netns del ns1\n[  132.495484] ------------[ cut here ]------------\n[  132.497609] kernel BUG at net/core/dev.c:12376!\n\nCommit 61220ab34948 (\"vti6: Enable namespace changing\") dropped\nNETIF_F_NETNS_LOCAL from vti6 devices. A vti6 tunnel can then\nmove through IFLA_NET_NS_FD. After the move dev_net(dev) points\nat the new netns while t-\u003enet stays at the creation netns.\n\nvti6_changelink() and vti6_update() still use dev_net(dev) and\ndev_net(t-\u003edev). They unlink from one per netns hash and relink\ninto another. The creation netns is left with a stale entry.\ncleanup_net() of that netns later walks freed memory.\n\nReachable from an unprivileged user namespace (unshare --user\n--map-root-user --net). Cross tenant scope on container hosts.",
  "id": "GHSA-225v-7w3r-pcq9",
  "modified": "2026-07-20T15:31:51Z",
  "published": "2026-07-19T18:31:46Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63917"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0cdce7618464f7fb06f461e8f4ad575cb1d570f4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/11b326fb0a374f4654f9be22d0f0f7abd9f7d3fe"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/225b467e3b631f38be22e4b38062a1fed02fdd21"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d9c5eecdb3c740e65038651db7c686b10d76d1bc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ee1778ba0f5cb53be771f97017d01eb356c797bf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f1e89a943ee574d0f2f16246eb3f2d7330fdeb03"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f5c68875e25f331e497ddfbe81e2d8163a87f136"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fc32be9ac2788524c6b24efd681cce7a6e731a92"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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