CVE-2026-74325 wifi: mt76: use kfree_rcu for offchannel link in mt76_put_vif_phy_link
A use-after-free vulnerability in the Linux kernel mt76 WiFi driver allows attackers to cause denial of service or execute code via improper memory handling.
- 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-2026-74325?
CVE-2026-74325 is a high-severity use after free vulnerability in Linux, published on 15 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: mt76: use kfree_rcu for offchannel link in mt76_put_vif_phy_link
mt76_put_vif_phy_link() frees the offchannel mlink with plain kfree() after rcu_assign_pointer(NULL). However, rcu_assign_pointer only prevents future RCU readers from obtaining the pointer -- it does not wait for existing readers that already hold it via rcu_dereference.
The TX datapath (e.g. mt7996_mac_write_txwi) dereferences mlink->wcid and mlink->idx under rcu_read_lock. If a TX softirq obtained the pointer via rcu_dereference just before the NULL assignment, it will dereference freed memory after the kfree.
struct mt76_vif_link already contains an rcu_head field that is unused at this free site -- a developer oversight, since the adjacent kfree_rcu_mightsleep call for rx_sc in the same function shows the pattern was understood.
Replace kfree(mlink) with kfree_rcu(mlink, rcu_head).
Which versions are affected by CVE-2026-74325?
How do I fix CVE-2026-74325?
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-2026-74325 being exploited?
There is no known exploitation of CVE-2026-74325 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74325, DEBIAN-CVE-2026-74325, GHSA-4hx5-9m7x-6xgv, UBUNTU-CVE-2026-74325.