CVE-2026-89628 HID: picolcd: clamp eeprom debugfs read to bytes actually received
A local attacker with root privileges can read adjacent kernel memory via a crafted HID device response in the picolcd driver.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89628?
CVE-2026-89628 is a vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
HID: picolcd: clamp eeprom debugfs read to bytes actually received
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.
Which versions are affected by CVE-2026-89628?
How do I fix CVE-2026-89628?
Apply the vendor's patch.
Is CVE-2026-89628 being exploited?
There is no known exploitation of CVE-2026-89628 in the wild and no public exploit code.
Sources
Also known as AZL-100241, BELL-CVE-2026-89628, DEBIAN-CVE-2026-89628, GHSA-84x9-cxq8-hpgq, UBUNTU-CVE-2026-89628.