CVE-2026-64568 wifi: mac80211: fix unsol_bcast_probe_resp double free on alloc failure
A double-free vulnerability in the Linux kernel's mac80211 Wi-Fi subsystem allows attackers to cause a system crash via memory corruption.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64568?
CVE-2026-64568 is a high-severity use after free vulnerability in Linux, published on 5 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: fix unsol_bcast_probe_resp double free on alloc failure
ieee80211_set_unsol_bcast_probe_resp() calls kfree_rcu() on the old template before allocating the replacement. If the kzalloc() then fails, it returns -ENOMEM while link->u.ap.unsol_bcast_probe_resp still points at the object already queued for freeing. A later update or AP teardown re-queues that same rcu_head; the second free is caught by KASAN when the RCU sheaf is processed in softirq:
BUG: KASAN: double-free in rcu_free_sheaf (mm/slub.c:5850) Free of addr ffff88800d06f300 by task exploit/145 ... __rcu_free_sheaf_prepare (mm/slub.c:2634 mm/slub.c:2940) rcu_free_sheaf (mm/slub.c:5850) rcu_core (kernel/rcu/tree.c:2617 kernel/rcu/tree.c:2869) handle_softirqs (kernel/softirq.c:622) The buggy address belongs to the cache kmalloc-128 of size 128
Queue the old object for kfree_rcu() only after the new one is published, matching ieee80211_set_probe_resp() and ieee80211_set_s1g_short_beacon().
Which versions are affected by CVE-2026-64568?
How do I fix CVE-2026-64568?
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-2026-64568 being exploited?
There is no known exploitation of CVE-2026-64568 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64568, DEBIAN-CVE-2026-64568, GHSA-c46h-f4qf-6cmr, UBUNTU-CVE-2026-64568.