CVE-2026-89559 libnvdimm/labels: Prevent integer overflow in __nd_label_validate()
An integer overflow in the Linux kernel's libnvdimm module allows an out-of-bounds write, potentially leading to code execution or denial of service.
- 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-2026-89559?
CVE-2026-89559 is a high-severity vulnerability in Linux, published on 11 Sep 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:
libnvdimm/labels: Prevent integer overflow in __nd_label_validate()
The on-media namespace index field nslot is a u32 read from the DIMM label storage area. __nd_label_validate() bounds it against the config area size, but sizeof_namespace_label() returns unsigned, so the product nslot * label_size is evaluated in 32-bit and wraps modulo 2^32 before the comparison. A crafted nslot passes the bound and is then used as the loop trip count in nd_label_data_init(), whose memset() walks off the end of the config_size buffer: an out-of-bounds write.
The field is not trusted -- it comes from the medium, or from userspace via ND_CMD_SET_CONFIG_DATA. Evaluate the product in 64-bit so the bound check is exact; conforming labels are unaffected.
The check was safe when introduced by commit 4a826c83db4e ("libnvdimm: namespace indices: read and validate"): it multiplied by sizeof(struct nd_namespace_label), a size_t, so on a 64-bit build the product did not wrap. Commit 564e871aa66f ("libnvdimm, label: add v1.2 nvdimm label definitions") narrowed it to 32 bits when the label size became a runtime value read via sizeof_namespace_label().
Which versions are affected by CVE-2026-89559?
How do I fix CVE-2026-89559?
Apply the vendor's patch.
Is CVE-2026-89559 being exploited?
There is no known exploitation of CVE-2026-89559 in the wild and no public exploit code.
Sources
Also known as AZL-100244, BELL-CVE-2026-89559, DEBIAN-CVE-2026-89559, GHSA-cp82-3r67-94rf, UBUNTU-CVE-2026-89559.