CVE-2026-90077 net: fix a resource leak in copy_net_ns() error handling path
A resource leak in the Linux kernel network namespace creation allows local attackers to exhaust system resources, causing denial of service.
- 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-2026-90077?
CVE-2026-90077 is a denial of service vulnerability in Linux, published on 17 Sep 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: fix a resource leak in copy_net_ns() error handling path
Currently, preinit_net() does two things:
(1) call ns_common_init() which might fail (2) initialize resources which does not fail
However, preinit_net() is returning early when (1) fails, and copy_net_ns() is jumping to the dec_ucounts: label. As a result, resources allocated by net_alloc() are leaking. We need to call key_remove_domain() and net_passive_dec() in order to release resources allocated by net_alloc().
We cannot simply jump to the put_userns: label when preinit_net() failed, for (2) is not yet done. But we can reorder (1) and (2), for there is no dependency between (1) and (2). Therefore, this patch decouples (1) from preinit_net() and changes preinit_net() back to a void function, and calls ns_common_init() after preinit_net() succeeded. Then, we can jump to immediately after ns_common_free() of the put_userns: label.
Which versions are affected by CVE-2026-90077?
How do I fix CVE-2026-90077?
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-2026-90077 being exploited?
There is no known exploitation of CVE-2026-90077 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-90077, DEBIAN-CVE-2026-90077, GHSA-gwpv-9h8f-9f72, UBUNTU-CVE-2026-90077.