CVE Catalog

CVE-2026-89790

Low risk· EPSS 10%
Published: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.20%

10th percentile - higher than 10% of all known CVEs

Summary

In the Linux kernel, the rt6_multipath_rebalance() function is vulnerable to a divide-by-zero. A concurrent update of ignore_routes_with_linkdown can make the first pass return zero while the second sees an eligible nexthop, causing a division by zero in rt6_upper_bound_set().

Risk Assessment

An attacker can trigger a kernel panic by exploiting the race condition, leading to denial of service.

Recommendation

Apply the Linux kernel update containing the fix that skips upper-bound calculation when the first pass reports a zero total.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS