CVE-2026-89790

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.

CVSS

No CVSS.

References

Link	Resource
https://git.kernel.org/stable/c/d2c26c2911dd1a363c488add4fb63eb5f0f28f87
https://git.kernel.org/stable/c/f30cf8fd9872299c0c27f9916252ba2b9f422dce
https://git.kernel.org/stable/c/f82b5dbb2fef65b52a62d5ffe05e0483c4385a83

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-16 09:17

Updated : 2026-09-16 09:17

NVD link : CVE-2026-89790

Mitre link : CVE-2026-89790

CVE.ORG link : CVE-2026-89790

JSON object : View

Products Affected

No product.

CWE

No CWE.

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