CVE-2026-90102 NFSv4/pnfs: key the data server cache on the NFS version
A null pointer dereference in the Linux kernel NFSv4/pnfs module can cause a denial of service when data servers with different NFS versions share an address.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90102?
CVE-2026-90102 is a high-severity vulnerability in Linux, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
NFSv4/pnfs: key the data server cache on the NFS version
nfs4_pnfs_ds_add() keys the per-net data server cache on the multipath address set alone, and struct nfs4_pnfs_ds records no version. That suffices for the files layout driver, which always connects with version 4, but flexfiles takes its version tuple from GETDEVICEINFO per device, and one address can legitimately serve both NFSv3 and NFSv4.
Two deviceids on one address with different ds_versions[0].version therefore share a single nfs4_pnfs_ds, and whichever mirror connects first pins ds_clp to its own version. The other one is handed that client anyway, so it selects rpc_call_ops for a version the connection does not speak, and the mismatched sequence-slot handling dereferences NULL.
Add the version to the cache key so the two cannot alias, giving each version its own nfs4_pnfs_ds and connection while both mirrors stay usable. Only the major version is compared, since that is what selects rpc_call_ops and rpc_ops; v4.0 and v4.1 keep sharing a client. The files layout driver passes the 4 it already hardcodes at connect time.
Which versions are affected by CVE-2026-90102?
How do I fix CVE-2026-90102?
Apply the vendor's patch.
Is CVE-2026-90102 being exploited?
There is no known exploitation of CVE-2026-90102 in the wild and no public exploit code.
Sources
Also known as AZL-101861, BELL-CVE-2026-90102, DEBIAN-CVE-2026-90102, GHSA-wj5v-2g3c-hmrh, UBUNTU-CVE-2026-90102.