{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-89790",
  "modified": "2026-10-07T14:35:31Z",
  "upstream": [
    "CVE-2026-89790"
  ],
  "published": "2026-09-16T08:46:47Z",
  "summary": "ipv6: avoid divide by zero in rt6_multipath_rebalance",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: avoid divide by zero in rt6_multipath_rebalance\n\nrt6_multipath_rebalance() calculates the total eligible nexthop weight\nin one pass and programs upper bounds in a second pass. Since\nRTM_NEWROUTE is RTNL-free, a concurrent\nignore_routes_with_linkdown update can make the first pass return zero\nwhile the second sees an eligible nexthop, causing\nrt6_upper_bound_set() to divide by zero.\n\nUBSAN: division-overflow in net/ipv6/route.c:4845:17\nOops: divide error: 0000 [#1] SMP KASAN NOPTI\n  rt6_upper_bound_set() net/ipv6/route.c:4845\n  rt6_multipath_rebalance()\n  fib6_add_rt2node()\n  ip6_route_multipath_add()\n  inet6_rtm_newroute()\n\nSkip upper-bound calculation when the first pass reports a zero total.\nThis respects the lock-free performance considerations here and solves\ninsecure scenarios.",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:13",
        "name": "linux"
      },
      "versions": [
        "1:6.18.29-1+rpt1",
        "1:6.18.33-1+rpt1",
        "1:6.18.34-1+rpt1",
        "1:6.18.39-1+rpt1",
        "1:6.18.50-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-2712",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v6",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v7",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v8",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-2712",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v6",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v7",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v8",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-2712",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-v6",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-v7",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-v8",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-2712",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-v6",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-v7",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-v8",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-2712",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v6",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v7",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v8",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.50-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.18.29-1+rpt1": {
            "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc",
            "upstream_version": "6.18.29",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.52"
          },
          "1:6.18.33-1+rpt1": {
            "linux_commit": "95b85bebbedcaedfa7ca79116ed38b7376fba412",
            "upstream_version": "6.18.33",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.52"
          },
          "1:6.18.34-1+rpt1": {
            "linux_commit": "c8c7494100e99ee05b11aaa4f0588a223a63d1af",
            "upstream_version": "6.18.34",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.52"
          },
          "1:6.18.39-1+rpt1": {
            "linux_commit": "60ea684a8ace97bb0db1a16e20753bdd6ab371ff",
            "upstream_version": "6.18.39",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.52"
          },
          "1:6.18.50-1+rpt1": {
            "linux_commit": "cff533aec2fa601846766b32ff57204e0a61bed7",
            "upstream_version": "6.18.50",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.52"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-89790"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f30cf8fd9872299c0c27f9916252ba2b9f422dce"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f82b5dbb2fef65b52a62d5ffe05e0483c4385a83"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d2c26c2911dd1a363c488add4fb63eb5f0f28f87"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-09-16T08:46:47Z"
  }
}