CVE-2026-89628

What the bug is

picolcd_debug_eeprom_read() trusts resp->raw_data[2] -- a length byte supplied by the device in its REPORT_EE_DATA reply -- clamped only to the caller's read() count: ret = resp->raw_data[2]; if (ret > s) ret = s; if (copy_to_user(u, resp->raw_data+3, ret)) It never checks resp->raw_size, the number of bytes picolcd_raw_event() actually copied into the 64-byte raw_data[] of the kmalloc'd struct picolcd_pending. A device (or a spoofed picoLCD) returning a length byte of 0xff, read with a count >= 255, makes copy_to_user() read past raw_data[] into adjacent slab memory and return it to userspace through the debugfs "eeprom" file: BUG: KASAN: slab-out-of-bounds in _copy_to_user Read of size 255 ... picolcd_debug_eeprom_read+0x214/0x2f0 [hid_picolcd] The debug-dump path in the same file already validates the device length byte against the received size before trusting it; this read does not. The file is created S_IRUSR (root-only) and a crafted device is needed, so it is neither unprivileged- nor remotely-triggerable. Clamp the copy length to resp->raw_size - 3 (the payload actually received, minus the 3-byte header), floored at 0 for short replies.

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/hid/hid-picolcd_debugfs.c

What this is

PICOLCD HID DRIVERMAINTAINERS section matched on drivers/hid/hid-picolcd* · linux-input@vger.kernel.org · Maintained

Kernel module

hid_picolcd

Check it on the machine

grep -wE 'CONFIG_DEBUG_FS|CONFIG_HID|CONFIG_HID_PICOLCD|CONFIG_HID_SUPPORT' /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 hid_picolcd

Prints 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.

• bookworm, trixieMnot built on arm64/cloud-arm64
• forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64
• bookworm · linux-6.12Mnot built on arm64/cloud-arm64

M

a module where it is built at all; some flavours do not build it

Build switches

CONFIG_DEBUG_FS, CONFIG_HID, CONFIG_HID_PICOLCD, CONFIG_HID_SUPPORT

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

2026-09-11 (37 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.22%, higher than 11.6% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

drivers/hid

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
2.6.35	5.10.270	1a02056c2bf7
2.6.35	5.15.221	65daa322f102
2.6.35	6.1.188	8dc662af0191
2.6.35	6.6.157	4daf432c94a4
2.6.35	6.12.109	a3e6e8d7198a
2.6.35	6.18.50	471f4a939c66
2.6.35	7.2.4	699a3c8b56e1
2.6.35	7.3	e9c667395ac1

Debian advisories