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CVE-2026-68467
mtd: mchp23k256: use SPI match data for chip caps
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/mtd. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-68467 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
The driver stores chip capacity information in both the OF match table and the SPI id table. Probe currently uses of_device_get_match_data(), so a non-OF SPI modalias match falls back to mchp23k256_caps even when the SPI id table selected a different part. Use spi_get_device_match_data() so SPI id-table driver_data is consumed when OF match data is absent. This keeps the existing default fallback while avoiding the wrong MTD geometry for id-table-only matches.
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/mchp23k256.c
- What this is
- MEMORY TECHNOLOGY DEVICES (MTD)MAINTAINERS section matched on drivers/mtd/ · linux-mtd@lists.infradead.org · Maintained
- Kernel module
- none to look for. The file would have gone into mchp23k256, and Debian does not compile it into that module, so finding mchp23k256 in lsmod would say nothing about this CVE.
Check it on the machine
grep -wE 'CONFIG_MTD|CONFIG_MTD_MCHP23K256' /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 does not build this code. In 4 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.
- bookworm, trixie, forky, sidn
- n
- not enabled on any flavour - this release does not build the code
- Build switches
- CONFIG_MTD, CONFIG_MTD_MCHP23K256
- 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
- 0.13%, higher than 2.3% 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 |
|---|---|---|
| 4.13 | 5.15.212 | 2e179b028da9 |
| 4.13 | 6.1.178 | a0c38083623c |
| 4.13 | 6.6.145 | 7c0a3a73dccc |
| 4.13 | 6.12.97 | dbe2254d1da9 |
| 4.13 | 6.18.40 | 04ebd3766861 |
| 4.13 | 7.1.5 | 09e044192a42 |
| 4.13 | 7.2 | d322e40f4edf |
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 exercised only through local MTD I/O (mtdchar read/write or MEMREAD/MEMWRITE ioctls on /dev/mtdN) after probe; mchp23k256 is an on-board SPI SRAM driver with no network, Bluetooth, or remote-protocol entry point.
- AC:LAttack complexity, low
- On affected deployments (mchp23lcv1024 matched via SPI id table without OF), every mtd read/write deterministically uses 2-byte addresses on a 3-byte/128K part; the attacker chooses offsets and lengths to mis-map logical MTD access across the chip with no race or uncontrollable memory layout.
- PR:LPrivileges required, low
- The path from mtdchar_open through mchp23k256_read/write performs no capability checks beyond device-node permissions; on embedded/industrial boards where SPI SRAM MTD nodes are group- or world-accessible, a local unprivileged user can trigger the defective addressing.
- UI:NUser interaction, none
- No victim interaction is required beyond the attacker issuing their own mtd reads or writes; probe misconfiguration is automatic at boot and persists for all subsequent transfers.
- S:UScope, unchanged
- Impact is confined to incorrect SPI SRAM access within the same kernel/host security authority; there is no VM escape, IOMMU bypass, or cross-sandbox boundary crossing.
- C:HConfidentiality impact, high
- Wrong addr_width makes SPI reads return data from unintended chip offsets while mtdchar still caps logical size at 32K, enabling out-of-bounds disclosure of up to ~96K of 128K SRAM contents (credentials, runtime state) outside the reported geometry.
- I:HIntegrity impact, high
- Mis-encoded write addresses cause out-of-bounds stores into the full 128K device despite mtd->size enforcing a 32K bound, corrupting SRAM regions the attacker should not be able to reach through the MTD interface.
- A:HAvailability impact, high
- Desynchronized SPI transactions from address-width mismatch can stall spi_sync() and hang the bus, and corrupted on-board SRAM can crash safety-critical embedded services or trigger watchdog resets on industrial controllers.