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CVE-2026-72171
mtd: slram: remove failed entries from the device list
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/mtd. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-72171 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 | fixed | 6.1.180-1 | Update the kernel and reboot. Fixed in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
register_device() links a new slram_mtdlist entry before allocating all of the state needed by the entry. If a later allocation, memremap(), or mtd_device_register() fails, the partially initialized entry remains on the global list. A later cleanup can then dereference or free invalid state from that failed entry. Unwind the partially initialized entry and clear the list tail on each failure path after the entry has been linked.
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/mtd/devices/slram.c
- What this is
- MEMORY TECHNOLOGY DEVICES (MTD)MAINTAINERS section matched on drivers/mtd/ · linux-mtd@lists.infradead.org · Maintained
- Kernel module
- slram
Check it on the machine
grep -wE 'CONFIG_MTD|CONFIG_MTD_SLRAM' /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 slramPrints 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 amd64/cloud-amd64, arm64/arm64, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le
- trixieMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_MTD, CONFIG_MTD_SLRAM
- 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
- 2026-08-15 (2 months 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
- 0.16%, higher than 5.2% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/mtd
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 5.10.261 | 9ee674ab10f7 |
| 2.6.12 | 5.15.212 | e97415b8254d |
| 2.6.12 | 6.1.178 | f40acf577bb0 |
| 2.6.12 | 6.6.145 | 200b8bc5b606 |
| 2.6.12 | 6.12.97 | 2fd0cbbb3444 |
| 2.6.12 | 6.18.40 | d8dcbbfa0d69 |
| 2.6.12 | 7.1.5 | bdcdfc246465 |
| 2.6.12 | 7.2 | 36f1648644d7 |
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 flaw is only reachable through local module initialization (finit_module/init_module → init_slram → parse_cmdline → register_device) or the slram= boot parameter; there is no network, adjacent-wireless, or physical-device input path to this MTD driver registration code.
- AC:LAttack complexity, low
- An attacker who can load the module controls map parameters and can reliably force register_device() to fail (e.g., memremap on an overlapping/invalid RAM region documented to fail), after which parse_cmdline deterministically calls unregister_devices() on the corrupt list entry.
- PR:LPrivileges required, low
- Exploitation requires loading the slram module via finit_module/init_module, which checks CAP_SYS_MODULE; on kernels allowing unprivileged user namespaces this capability is available to a local unprivileged user, matching CNA guidance for module-init bugs rather than init-namespace root only.
- UI:NUser interaction, none
- No victim interaction is required; the attacker triggers module load with crafted parameters and the kernel fault occurs automatically on the register_device() failure cleanup path without anyone mounting filesystems or opening devices.
- S:UScope, unchanged
- Memory corruption occurs entirely within kernel context during module-init teardown of the slram driver; it does not cross VM/hypervisor, IOMMU, or other security boundaries into a separate authority.
- C:HConfidentiality impact, high
- Failed entries leave NULL or dangling mtdinfo/priv pointers on slram_mtdlist, and unregister_devices() dereferences/frees that invalid state, constituting use-after-free and out-of-bounds kernel memory access that can expose reclaimed heap contents.
- I:HIntegrity impact, high
- The mtd_device_register() failure path frees mtdinfo and priv while the list node remains, so unregister_devices() performs double-free and use-after-free on those structures, which is heap corruption exploitable for arbitrary kernel writes and control-flow hijacking.
- A:HAvailability impact, high
- unregister_devices() on a partially initialized entry can NULL-dereference mtdinfo, double-free kmalloc objects, or call mtd_device_unregister/memunmap on invalid pointers, reliably causing kernel oops or panic and repeatable denial of service.