The Shadow Kindle Jailbreak Gets Root Over USB With Decoy Folders, a Leaky File Date and One Extra Parameter

The target is tizen-mtp, Collabora’s fork of the Tizen MTP responder, and its source is public. That matters twice. Ava could read the code instead of guessing at it, and because “tizen-mtp runs as root,” a bug in it needs no second exploit to own the device.

The first bug is a leak. When the daemon reports a file’s creation or modification date, the structures that hold those dates are never cleared. If the file can’t be found on disk, the reply carries whatever was already on the stack. Shadow manufactures that case: it sends the information for a new file and never sends the file, so MTP thinks the object exists and the filesystem doesn’t.

What lands in that leftover stack slot depends on what the daemon did just before, so Shadow arranges it. It creates decoy folders in the root of the Kindle’s storage, some nested, some with long names, then asks for object lists and dates until the slot holds what it wants. Ava credits DeepSeek with finding the folder pattern. The reply then hands back a pointer into the daemon’s own code, and subtracting a fixed offset gives the base address that ASLR was hiding. The daemon imports system(), so knowing the base is enough to find it.

The second bug is an overflow. The daemon’s check on an incoming command allows one more parameter than its buffer holds, and the copy loop re-reads its own count from the field that last parameter overwrites. A crafted packet sets a bigger count and the loop writes past the buffer, over the saved return address. Two small gadgets in the daemon then load system() and a pointer to the command, and the Kindle runs /mnt/base-us/jb.sh as root.

There’s one practical wrinkle. “Shadow physically cannot do that, because Wi-Fi is disabled while MTP is active,” ava writes, so the script can’t be downloaded mid-exploit. You copy it over first, unplug, plug back in for a fresh daemon, and then run the attack.

Ava’s own reason for publishing after the patch is in the first lines of the post: “it’s always good to have alternatives to working jailbreaks.” For anyone holding a Kindle on 5.19.6 or later, short of 5.20.1, who wants KOReader on it, that alternative now exists. Everyone else gets it closed by updating.