CVE-2026-68409
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk16th percentile - higher than 16% of all known CVEs
Summary
In the Linux kernel, the wifi mac80211 subsystem has a synchronization issue when removing an MLO link. sta_remove_link() frees the RX stats percpu buffer immediately, while the link container is freed only after RCU. This can lead to use-after-free in the fast RX path. The fix defers the percpu buffer free to an RCU callback.
Risk Assessment
The vulnerability can lead to system crashes or potentially privilege escalation if an attacker can exploit the race condition to access freed memory.
Recommendation
Update the Linux kernel to a version containing the fix that defers the percpu stats free until after RCU grace period.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: defer link RX stats percpu free to RCU sta_remove_link() frees a removed MLO link's RX stats percpu buffer right away, but defers only the link container to RCU: sta_info_free_link(&alloc->info); kfree_rcu(alloc, rcu_head); The RX fast path reads link_sta under rcu_read_lock and writes the percpu stats. A reader that resolved link_sta before the removal keeps the pointer. The container stays alive from the kfree_rcu, so the read still works. But the percpu block it points to is already freed. This needs uses_rss. That is when pcpu_rx_stats exists. The full STA teardown frees the deflink stats only after synchronize_net(). The link removal path had no such barrier. The race is hard to win in practice, but the free should still wait for RCU. Free the link together with its data from a single RCU callback, so the percpu block is reclaimed only after readers drain.