CVE-2026-43403 nsfs: tighten permission checks for ns iteration ioctls
A Linux kernel vulnerability allows privileged services to leak namespace information to each other due to insufficient permission checks.
- 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-2026-43403?
CVE-2026-43403 is a high-severity vulnerability in Linux kernel, published on 8 May 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:
nsfs: tighten permission checks for ns iteration ioctls
Even privileged services should not necessarily be able to see other privileged service's namespaces so they can't leak information to each other. Use may_see_all_namespaces() helper that centralizes this policy until the nstree adapts.
Which versions are affected by CVE-2026-43403?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43403?
Apply the vendor's patch.
Is CVE-2026-43403 being exploited?
There is no known exploitation of CVE-2026-43403 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43403, DEBIAN-CVE-2026-43403, GHSA-6ghr-3376-w3mq, UBUNTU-CVE-2026-43403.