CVE-2026-89652 ceph: bound copied dentry name length in NFS export get_name
A malicious Ceph MDS can trigger a buffer overflow in the Linux kernel NFS export path, potentially allowing code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89652?
CVE-2026-89652 is a critical memory corruption vulnerability in Linux, published on 11 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:
ceph: bound copied dentry name length in NFS export get_name
ceph_get_name() copies the MDS-supplied name into the caller's NAME_MAX-sized buffer with memcpy(name, rinfo->dname, rinfo->dname_len) and then writes name[rinfo->dname_len] = 0, without checking dname_len against NAME_MAX. A malicious or buggy MDS that returns a LOOKUPNAME reply with dname_len > NAME_MAX overflows the buffer. __get_snap_name() copies rde->name / rde->name_len the same unchecked way.
Impact: a malicious or compromised Ceph MDS overflows the NAME_MAX name buffer in a client's NFS-export get_name path, a slab out-of-bounds write reported by KASAN. Reachable when a CephFS mount is re-exported over NFS.
Add ceph_export_copy_name(), which rejects lengths above NAME_MAX with -ENAMETOOLONG before the copy, and use it in both ceph_get_name() and __get_snap_name().
Which versions are affected by CVE-2026-89652?
How do I fix CVE-2026-89652?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-89652 being exploited?
There is no known exploitation of CVE-2026-89652 in the wild and no public exploit code.
Sources
Also known as AZL-100566, BELL-CVE-2026-89652, DEBIAN-CVE-2026-89652, GHSA-rgf4-v7fw-49xj, UBUNTU-CVE-2026-89652.