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CVE-2026-89559
libnvdimm/labels: Prevent integer overflow in __nd_label_validate()
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem drivers/nvdimm. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89559 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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().
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/nvdimm/label.c
- What this is
- LIBNVDIMM: NON-VOLATILE MEMORY DEVICE SUBSYSTEMMAINTAINERS section matched on drivers/nvdimm/* · nvdimm@lists.linux.dev · Supported
- Kernel module
- libnvdimm
Check it on the machine
grep -w CONFIG_LIBNVDIMM /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w libnvdimmPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, ppc64el/powerpc64le
- trixieMnot built on armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
- forky, sidMnot built on armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
- bookworm · linux-6.12Mnot built on armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_LIBNVDIMM
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-11 (37 days ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 5.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/nvdimm
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.13 | 5.10.270 | b4975f2ff6c8 |
| 4.13 | 5.15.221 | 6030597ec683 |
| 4.13 | 6.1.188 | 1c391696d279 |
| 4.13 | 6.6.157 | 93967bfb17da |
| 4.13 | 6.12.109 | e057efcc9c71 |
| 4.13 | 6.18.50 | 09e649117c54 |
| 4.13 | 7.2.4 | 69a734359639 |
| 4.13 | 7.3 | 037770686126 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The overflow is consumed in nvdimm_probe()->nd_label_data_init() from a namespace index a local process plants via ioctl(ND_CMD_SET_CONFIG_DATA) on /dev/nmem*, or that already resides in the DIMM label area. There is no network or adjacent-network path into this parser.
- AC:LAttack complexity, low
- A crafted nslot (e.g. 2^25 with 128-byte labels) makes the 32-bit nslot*sizeof_namespace_label() product wrap so the bound check passes, and the attacker also controls the signature, checksum, and free bitmap, making the later memset() walk deterministic. No race or uninfluenceable layout is required.
- PR:LPrivileges required, low
- nd_open(), __nd_ioctl(), and nd_cmd_clear_to_send() perform no capable() check; SET_CONFIG_DATA is gated only by O_RDWR on /dev/nmem* (typically 0660 disk via udev). Any local account, disk-group user, or container granted that node can plant the malicious index that probe later consumes.
- UI:NUser interaction, none
- The attacker plants the crafted index from their own process and the OOB write runs in nd_label_data_init() on the ordinary dimm probe/bind path they drive with ndctl write-labels/enable; no separate victim action such as mounting a filesystem is required.
- S:UScope, unchanged
- The kvzalloc out-of-bounds write corrupts kernel heap inside the same kernel security authority and does not cross a VM, IOMMU, or sandbox boundary.
- C:HConfidentiality impact, high
- The memset() loop is an unbounded heap out-of-bounds write whose distance is set by the attacker-chosen nslot (128/256-byte stores marching far past the config buffer). Corruption of adjacent heap objects can be turned into an arbitrary-read primitive, not a leak bounded to a few bytes.
- I:HIntegrity impact, high
- Each free-slot iteration does memset(ndd->data+offset, 0, label_size) with offset advancing past config_size, which is a kernel heap out-of-bounds write that can corrupt adjacent objects and hijack control flow.
- A:HAvailability impact, high
- The same walk writes tens of megabytes past the kvzalloc buffer and will oops or panic on unmapped pages or corrupted kernel state; any such kernel crash is High availability impact.