CVE-2026-89693 nfsd: check nfsd4_acl_to_attr() return value in nfsd4_create()
An attacker can bypass ACL restrictions during file creation in the Linux kernel NFS server by exploiting unchecked return values.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89693?
CVE-2026-89693 is a missing authorization vulnerability in Linux, published on 11 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
nfsd: check nfsd4_acl_to_attr() return value in nfsd4_create()
nfsd4_create() stores the return value of nfsd4_acl_to_attr() in status, but the switch(create->cr_type) block unconditionally overwrites it in every branch. ACL translation errors are silently discarded, and the CREATE proceeds without the requested ACL.
Add an early exit check after nfsd4_acl_to_attr(), matching the pattern already used in nfsd4_setattr().
[ cel: prefer NFS4ERR_BADTYPE over NFS4ERR_ATTRNOTSUPP ]
Which versions are affected by CVE-2026-89693?
How do I fix CVE-2026-89693?
Apply the vendor's patch.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-89693 being exploited?
There is no known exploitation of CVE-2026-89693 in the wild and no public exploit code.
Sources
Also known as AZL-100163, BELL-CVE-2026-89693, DEBIAN-CVE-2026-89693, GHSA-hqc5-5f52-xmgw, UBUNTU-CVE-2026-89693.