{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "bd11ff421d36abdb585b9104fa70057bf01b3110"
            },
            {
              "fixed": "f30cf8fd9872299c0c27f9916252ba2b9f422dce"
            },
            {
              "fixed": "f82b5dbb2fef65b52a62d5ffe05e0483c4385a83"
            },
            {
              "fixed": "d2c26c2911dd1a363c488add4fb63eb5f0f28f87"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.16.0"
            },
            {
              "fixed": "6.18.52"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89790.json"
  },
  "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.",
  "id": "CVE-2026-89790",
  "modified": "2026-09-18T03:30:57.045489679Z",
  "published": "2026-09-16T08:48:26.343Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d2c26c2911dd1a363c488add4fb63eb5f0f28f87"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f30cf8fd9872299c0c27f9916252ba2b9f422dce"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f82b5dbb2fef65b52a62d5ffe05e0483c4385a83"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89790.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89790"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "ipv6: avoid divide by zero in rt6_multipath_rebalance"
}