{"id":"CVE-2026-89790","title":"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…","summary":"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…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= bd11ff421d36abdb585b9104fa70057bf01b3110 < f30cf8fd9872299c0c27f9916252ba2b9f422dce","Linux >= bd11ff421d36abdb585b9104fa70057bf01b3110 < f82b5dbb2fef65b52a62d5ffe05e0483c4385a83","Linux >= bd11ff421d36abdb585b9104fa70057bf01b3110 < d2c26c2911dd1a363c488add4fb63eb5f0f28f87","Linux 6.16"],"published":"2026-09-16","updated":"2026-09-16","sourceUpdated":"2026-09-16T09:17:09.827","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-89790","references":[{"url":"https://git.kernel.org/stable/c/d2c26c2911dd1a363c488add4fb63eb5f0f28f87","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f30cf8fd9872299c0c27f9916252ba2b9f422dce","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f82b5dbb2fef65b52a62d5ffe05e0483c4385a83","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-16T08:52:29.591Z","epss":0.00198,"epssPercentile":0.09844,"slug":"CVE-2026-89790","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}