CVE-2026-68409 wifi: mac80211: defer link RX stats percpu free to RCU
A race condition in Linux kernel Wi-Fi MLO link removal allows use-after-free of percpu stats, potentially leading to code execution or crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68409?
CVE-2026-68409 is a high-severity use after free vulnerability in Linux, published on 10 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-416
Which versions are affected by CVE-2026-68409?
How do I fix CVE-2026-68409?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-68409 being exploited?
There is no known exploitation of CVE-2026-68409 in the wild and no public exploit code.
Sources
Also known as AZL-95042, BELL-CVE-2026-68409, DEBIAN-CVE-2026-68409, GHSA-g5f7-qj4q-4w5v, UBUNTU-CVE-2026-68409.