{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:11",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.10.257-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.170-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.85-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.19.8-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:11",
        "name": "linux-6.1"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.170-1~deb11u1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop  When a standalone IPv6 nexthop object is created with a loopback device (e.g., \"ip -6 nexthop add id 100 dev lo\"), fib6_nh_init() misclassifies it as a reject route. This is because nexthop objects have no destination prefix (fc_dst=::), causing fib6_is_reject() to match any loopback nexthop. The reject path skips fib_nh_common_init(), leaving nhc_pcpu_rth_output unallocated. If an IPv4 route later references this nexthop, __mkroute_output() dereferences NULL nhc_pcpu_rth_output and panics.  Simplify the check in fib6_nh_init() to only match explicit reject routes (RTF_REJECT) instead of using fib6_is_reject(). The loopback promotion heuristic in fib6_is_reject() is handled separately by ip6_route_info_create_nh(). After this change, the three cases behave as follows:  1. Explicit reject route (\"ip -6 route add unreachable 2001:db8::/64\"):    RTF_REJECT is set, enters reject path, skips fib_nh_common_init().    No behavior change.  2. Implicit loopback reject route (\"ip -6 route add 2001:db8::/32 dev lo\"):    RTF_REJECT is not set, takes normal path, fib_nh_common_init() is    called. ip6_route_info_create_nh() still promotes it to reject    afterward. nhc_pcpu_rth_output is allocated but unused, which is    harmless.  3. Standalone nexthop object (\"ip -6 nexthop add id 100 dev lo\"):    RTF_REJECT is not set, takes normal path, fib_nh_common_init() is    called. nhc_pcpu_rth_output is properly allocated, fixing the crash    when IPv4 routes reference this nexthop.",
  "id": "DEBIAN-CVE-2026-23300",
  "modified": "2026-05-29T17:48:21.198077166Z",
  "published": "2026-03-25T11:16:25.623Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-23300"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-23300"
  ]
}