Description
In the Linux kernel, the following vulnerability has been resolved:
ipv6: avoid divide by zero in rt6_multipath_rebalance
rt6_multipath_rebalance() calculates the total eligible nexthop weight in one pass and programs upper bounds in a second pass. Since RTM_NEWROUTE is RTNL-free, a concurrent ignore_routes_with_linkdown update can make the first pass return zero while the second sees an eligible nexthop, causing rt6_upper_bound_set() to divide by zero.
UBSAN: division-overflow in net/ipv6/route.c:4845:17 Oops: divide error: 0000 [#1] SMP KASAN NOPTI rt6_upper_bound_set() net/ipv6/route.c:4845 rt6_multipath_rebalance() fib6_add_rt2node() ip6_route_multipath_add() inet6_rtm_newroute()
Skip upper-bound calculation when the first pass reports a zero total. This respects the lock-free performance considerations here and solves insecure scenarios.
Metrics
No CVSS score has been published yet.
Affected software
Source: the vendor's advisory (CNA). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | >= bd11ff421d36abdb585b9104fa70057bf01b3110, < f30cf8fd9872299c0c27f9916252ba2b9f422dce; >= bd11ff421d36abdb585b9104fa70057bf01b3110, < f82b5dbb2fef65b52a62d5ffe05e0483c4385a83; >= bd11ff421d36abdb585b9104fa70057bf01b3110, < d2c26c2911dd1a363c488add4fb63eb5f0f28f87 |
| Linux | Linux | 6.16 |
References
Timeline
- Published
- Sep 16, 2026
- Last modified
- Oct 19, 2026
- NVD status
- Received