CVE-2026-72405 net: udp_tunnel: prevent double queueing in udp_tunnel_nic_device_sync
A race condition in the Linux kernel UDP tunnel driver allows a use-after-free, potentially enabling local attackers to execute code or escalate privileges.
- 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-2026-72405?
CVE-2026-72405 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:
net: udp_tunnel: prevent double queueing in udp_tunnel_nic_device_sync
Yue Sun reported a use-after-free and debugobjects warning in udp_tunnel_nic_device_sync_work() during concurrent device operations.
The workqueue core clears the internal pending bit before invoking the worker. At that point, a concurrent thread can queue the work again. When the already running worker eventually clears the work_pending flag to 0, it mistakenly clears the flag for the newly queued instance. udp_tunnel_nic_unregister() then observes work_pending as 0 and frees the structure while the second work item is still active in the queue, leading to UAF.
Fix this by returning early in udp_tunnel_nic_device_sync() if work_pending is already set, preventing redundant work queueing.
Which versions are affected by CVE-2026-72405?
How do I fix CVE-2026-72405?
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-2026-72405 being exploited?
There is no known exploitation of CVE-2026-72405 in the wild and no public exploit code.
Sources
Also known as AZL-96275, BELL-CVE-2026-72405, DEBIAN-CVE-2026-72405, GHSA-w888-j23q-c78g, UBUNTU-CVE-2026-72405.