So, it looks like zx2c4 has found a local privilege escalation exploit. See source here, and saurik has managed to package
it together for Android. See here. Although this may be old news to some, I hadn't seen it before.
So what does this all mean:
1) This assumes that you have the drivers for your device installed on your computer.
2) This needs to be done over ADB, as a terminal emulator on-device does not have the appropriate access.
1) Download the attached files to your computer and unzip them in the same directory as your adb.exe file;
2) Open a command prompt in the same directory;
3) Copy the files to your device:
adb push mempodroid /data/local/tmp/mempodroid
adb push su /data/local/tmp/su
adb push Superuser.apk /data/local/tmp/Superuser.apk
4) Open a shell: adb shell
5) Change permission on mempodroid to allow it to run: chmod 777 /data/local/tmp/mempodroid
6) Run the exploit: ./data/local/tmp/mempodroid 0xd7f4 0xad4b sh
Note: Once you do step 6, your prompt should change from $ to #. If not, it did not work.
7) Mount the system partition as rw: mount -o remount,rw -t ext4 /dev/block/mmcblk0p1 /system
8) Copy su to /system: cat /data/local/tmp/su > /system/bin/su
9) Change permissions on su: chmod 06755 /system/bin/su
10) Copy Superuser.apk: cat /data/local/tmp/Superuser.apk > /system/app/Superuser.apk
11) Change permissions on Superuser.apk: chmod 0644 /system/app/Superuser.apk
12) Mount the system partition as r/o: mount -o remount,ro -t ext4 /dev/block/mmcblk0p1 /system
13) Rescind root: exit
14) Exit the ADB shell: exit
15) Done. You now should have root without having to unlock your bootloader.