CVE-2026-99073

In the Linux kernel, the following vulnerability has been resolved:

ipv4: stop exception dump when nexthop group shrinks

Commit 4ce5dc9316de ("inet: switch inet dump fib() to RCU protection") allowed IPv4 FIB dumps to run concurrently with nexthop replacement.

fib dump info fnhe() uses fib info num path() as the loop bound, then fib info nhc() independently reloads nh->nh grp. If RTM NEWNEXTHOP replaces a group with fewer paths between those loads, fib info nhc() returns NULL and the dump dereferences it through nhc flags.

Stop the walk when the indexed path is absent. Nexthop groups are dense, so the current snapshot has no later path.