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GHSA-3QGV-QJ84-5MMH

Vulnerability from github – Published: 2026-03-25 12:30 – Updated: 2026-07-14 15:31
VLAI
Details

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

ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()

l3mdev_master_dev_rcu() can return NULL when the slave device is being un-slaved from a VRF. All other callers deal with this, but we lost the fallback to loopback in ip6_rt_pcpu_alloc() -> ip6_rt_get_dev_rcu() with commit 4832c30d5458 ("net: ipv6: put host and anycast routes on device with address").

KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f] RIP: 0010:ip6_rt_pcpu_alloc (net/ipv6/route.c:1418) Call Trace: ip6_pol_route (net/ipv6/route.c:2318) fib6_rule_lookup (net/ipv6/fib6_rules.c:115) ip6_route_output_flags (net/ipv6/route.c:2607) vrf_process_v6_outbound (drivers/net/vrf.c:437)

I was tempted to rework the un-slaving code to clear the flag first and insert synchronize_rcu() before we remove the upper. But looks like the explicit fallback to loopback_dev is an established pattern. And I guess avoiding the synchronize_rcu() is nice, too.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-23304"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-25T11:16:26Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()\n\nl3mdev_master_dev_rcu() can return NULL when the slave device is being\nun-slaved from a VRF. All other callers deal with this, but we lost\nthe fallback to loopback in ip6_rt_pcpu_alloc() -\u003e ip6_rt_get_dev_rcu()\nwith commit 4832c30d5458 (\"net: ipv6: put host and anycast routes on\ndevice with address\").\n\n  KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]\n  RIP: 0010:ip6_rt_pcpu_alloc (net/ipv6/route.c:1418)\n  Call Trace:\n   ip6_pol_route (net/ipv6/route.c:2318)\n   fib6_rule_lookup (net/ipv6/fib6_rules.c:115)\n   ip6_route_output_flags (net/ipv6/route.c:2607)\n   vrf_process_v6_outbound (drivers/net/vrf.c:437)\n\nI was tempted to rework the un-slaving code to clear the flag first\nand insert synchronize_rcu() before we remove the upper. But looks like\nthe explicit fallback to loopback_dev is an established pattern.\nAnd I guess avoiding the synchronize_rcu() is nice, too.",
  "id": "GHSA-3qgv-qj84-5mmh",
  "modified": "2026-07-14T15:31:41Z",
  "published": "2026-03-25T12:30:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23304"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0b5a7826020706057cc5a9d9009e667027f221ee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2ffb4f5c2ccb2fa1c049dd11899aee7967deef5a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3310fc11fc47387d1dd4759b0bc961643ea11c7f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4a48fe59f29f673a3d042d679f26629a9c3e29d4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/581800298313c9fd75e94985e6d37d21b7e35d34"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a73fe9f4ae84a239d5b2686f47a58c158aee2eb4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ae88c8256547b63980770a9ea7be73a15900d27e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d542e2ac7f9e288d49735be0775611547ca4e0ee"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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