CVE-2026-43374

/// Technical description

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

net: nexthop: fix percpu use-after-free in remove_nh_grp_entry

When removing a nexthop from a group, remove_nh_grp_entry() publishes

the new group via rcu_assign_pointer() then immediately frees the

removed entry's percpu stats with free_percpu(). However, the

synchronize_net() grace period in the caller remove_nexthop_from_groups()

runs after the free. RCU readers that entered before the publish still

see the old group and can dereference the freed stats via

nh_grp_entry_stats_inc() -> get_cpu_ptr(nhge->stats), causing a

use-after-free on percpu memory.

Fix by deferring the free_percpu() until after synchronize_net() in the

caller. Removed entries are chained via nh_list onto a local deferred

free list. After the grace period completes and all RCU readers have

finished, the percpu stats are safely freed.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References