CVE-2026-31579 wireguard: device: use exit_rtnl callback instead of manual rtnl_lock in pre_exit
A race condition in the Linux kernel WireGuard module causes a hung task and denial of service during network namespace cleanup.
- 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-2026-31579?
CVE-2026-31579 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Apr 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:
wireguard: device: use exit_rtnl callback instead of manual rtnl_lock in pre_exit
wg_netns_pre_exit() manually acquires rtnl_lock() inside the pernet .pre_exit callback. This causes a hung task when another thread holds rtnl_mutex - the cleanup_net workqueue (or the setup_net failure rollback path) blocks indefinitely in wg_netns_pre_exit() waiting to acquire the lock.
Convert to .exit_rtnl, introduced in commit 7a60d91c690b ("net: Add ->exit_rtnl() hook to struct pernet_operations."), where the framework already holds RTNL and batches all callbacks under a single rtnl_lock()/rtnl_unlock() pair, eliminating the contention window.
The rcu_assign_pointer(wg->creating_net, NULL) is safe to move from .pre_exit to .exit_rtnl (which runs after synchronize_rcu()) because all RCU readers of creating_net either use maybe_get_net() - which returns NULL for a dying namespace with zero refcount - or access net->user_ns which remains valid throughout the entire ops_undo_list sequence.
[ Jason: added __net_exit and __read_mostly annotations that were missing. ]
Weakness: CWE-476
Which versions are affected by CVE-2026-31579?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31579?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-31579 being exploited?
There is no known exploitation of CVE-2026-31579 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-83828, BELL-CVE-2026-31579, DEBIAN-CVE-2026-31579, GHSA-h53c-6597-vmfw, ROOT-OS-DEBIAN-11-CVE-2026-31579, ROOT-OS-DEBIAN-12-CVE-2026-31579 and 4 more.