CVE-2026-46256 NFS/localio: prevent direct reclaim recursion into NFS via nfs_writepages
A deadlock in Linux kernel NFS LOCALIO can cause system hangs during memory reclaim, requiring a patch to fix.
- 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-2026-46256?
CVE-2026-46256 is a medium-severity denial of service vulnerability in Linux kernel, published on 3 Jun 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:
NFS/localio: prevent direct reclaim recursion into NFS via nfs_writepages
LOCALIO is an NFS loopback mount optimization that avoids using the network for READ, WRITE and COMMIT if the NFS client and server are determined to be on the same system. But because LOCALIO is still fundamentally "just NFS loopback mount" it is susceptible to recursion deadlock via direct reclaim, e.g.: NFS LOCALIO down to XFS and then back into NFS via nfs_writepages.
Fix LOCALIO's potential for direct reclaim deadlock by ensuring that all its page cache allocations are done from GFP_NOFS context.
Thanks to Ben Coddington for pointing out commit ad22c7a043c2 ("xfs: prevent stack overflows from page cache allocation").
Weakness: CWE-667
Which versions are affected by CVE-2026-46256?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46256?
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-2026-46256 being exploited?
There is no known exploitation of CVE-2026-46256 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-46256, DEBIAN-CVE-2026-46256, GHSA-44f9-rxj6-p8rg, ROOT-OS-DEBIAN-13-CVE-2026-46256, UBUNTU-CVE-2026-46256.