Look up another CVE · open CVE-2026-80723 in the interactive tracker
CVE-2026-80723
of: reserved_mem: prevent OOB when too many dynamic regions are defined
Published 2026-08-28 (2 months ago) by the Linux kernel CNA. Subsystem drivers/of. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-80723 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixed | 6.12.105-1 | Update the kernel and reboot. Fixed in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
On boot, fdt_scan_reserved_mem() saves each dynamically-placed /reserved-memory subnode into a local array of size MAX_RESERVED_REGIONS. If the device tree defines more than MAX_RESERVED_REGIONS dynamically-placed regions, fdt_scan_reserved_mem() writes past the end of the local array. Add a bounds check that logs an error and skips the excess regions, restoring the original behavior.
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/of/of_reserved_mem.c
- What this is
- OPEN FIRMWARE AND FLATTENED DEVICE TREEMAINTAINERS section matched on drivers/of/ · devicetree@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_OF|CONFIG_OF_RESERVED_MEM' /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.
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.
- bookwormYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, i386/686, i386/686-pae, i386/rt/686-pae
- trixieYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, s390x/s390x
- forky, sidYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, s390x/s390x
- bookworm · linux-6.12Ynot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64
- Y
- built in where it is built at all; some flavours do not build it
- Build switches
- CONFIG_OF, CONFIG_OF_RESERVED_MEM
- Reads as
- all on means the file is compiled; any one off means it is not.
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
- 2026-08-28 (2 months ago)source
- CVSS
- 8.4 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.5% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/of
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.12.13 | 6.12.103 | 68d27250c9e8 |
| 6.13 | 6.18.44 | cfa7e2734877 |
| 6.13 | 7.1.8 | de8ccbd6bf4e |
| 6.13 | 7.2 | db3dbdfea1b8 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | 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 only runs in __init boot-time fdt_scan_reserved_mem() while parsing /reserved-memory from the bootloader-provided DTB; there is no post-boot syscall, ioctl, netlink, or network-stack path to this code on OF/DT platforms (arm/arm64/RISC-V/ppc/mips/etc.).
- AC:LAttack complexity, low
- An attacker who can supply a device tree simply defines more than MAX_RESERVED_REGIONS (64) dynamically-placed /reserved-memory subnodes (size without reg); each extra node deterministically performs another unchecked write past dynamic_nodes[] without races or layout luck.
- PR:NPrivileges required, none
- Triggering requires only a crafted device tree delivered at boot (e.g., compromised firmware/OTA image, supply-chain DTB, unauthenticated PXE/TFTP netboot), not privileges on the victim OS; unprivileged local users and user-namespace capabilities cannot reach this __init-only path.
- UI:NUser interaction, none
- Once a malicious DTB is installed, the stack overflow occurs automatically during early_init_fdt_scan_reserved_mem() before userspace starts; no cooperative action by another user or administrator is required beyond normal boot.
- S:UScope, unchanged
- Impact is confined to early-boot kernel stack/memory corruption within the same host kernel; this is not a VM escape, guest-to-host breakout, IOMMU boundary bypass, or other cross-security-authority scenario.
- C:HConfidentiality impact, high
- Each OOB store writes an attacker-influenced FDT node offset past dynamic_nodes[MAX_RESERVED_REGIONS] onto the kernel stack, corrupting adjacent locals and potentially frame/link registers; per kernel guidance, stack OOB writes enable high confidentiality impact.
- I:HIntegrity impact, high
- This is a stack buffer overflow (CWE-121/787) during __init: repeated int writes past the 64-element dynamic_nodes[] array can corrupt return addresses and control flow in early boot before full hardening, enabling arbitrary kernel code execution.
- A:HAvailability impact, high
- Unchecked OOB writes into the boot-time stack typically cause immediate kernel panic/oops during fdt_scan_reserved_mem() (corrupted count/fdt pointers or trashed frame), denying availability on every boot with a crafted or over-limit DT.