Fix Broken Sudo Permissions Quickly

Fix Broken Sudo Permissions Quickly | Generated by AI

Home 2026.02

The error message:

sudo: /usr/bin/sudo must be owned by uid 0 and have the setuid bit set

means the sudo binary has incorrect ownership or permissions. Normally, it must be:

Owned by root (UID 0)
Have the setuid bit set (so it runs as root even when called by a normal user)

This often happens from accidental commands like chown, chmod -R, or messing with /usr/bin.

You can’t fix this with sudo (it’s broken), so you need root access another way. Here are the main fixes for Ubuntu (works on 20.04–26.04+ versions).

Method 1: Boot into Recovery Mode (Recommended & Safest)

Reboot your computer.
Hold Shift (or Esc on some systems) during boot to show the GRUB menu.
Select Advanced options for Ubuntu.
Choose a line ending in (recovery mode) → press Enter.
In the recovery menu, select root → Drop to root shell prompt → press Enter.
- You’ll get a # prompt as root (no password needed here).
Remount the filesystem read-write (important!):
```
mount -o remount,rw /
```
Fix the sudo binary:
```
chown root:root /usr/bin/sudo
chmod 4755 /usr/bin/sudo
```
- 4755 = owner read/write/execute + setuid bit + group/other read/execute.
- After this, ls -l /usr/bin/sudo should show something like:
```
-rwsr-xr-x 1 root root ... /usr/bin/sudo
```
  (the s in place of x = setuid bit)

Optional but good: also fix su if broken:

chown root:root /usr/bin/su
chmod 4755 /usr/bin/su

Exit the shell:
```
exit
```
From recovery menu: choose resume → normal boot.
After reboot, test with:
```
sudo ls
```

It should ask for your password and work.

Method 2: If You Have Root Password Set (or Can Log In as Root on TTY)

Switch to a text console: press Ctrl + Alt + F3 (or F2–F6).
Log in as root (if you have a root password) or your user if root login is allowed.

Then run the same fix commands as above:

mount -o remount,rw /
chown root:root /usr/bin/sudo
chmod 4755 /usr/bin/sudo
exit

Go back to GUI: Ctrl + Alt + F1 or F2.

Method 3: If Recovery Mode Fails or You Prefer Live USB

Boot from an Ubuntu Live USB (same version if possible).

Open terminal → mount your installed system (replace /dev/sda1 with your root partition – check with lsblk):

sudo mkdir /mnt/root
sudo mount /dev/sda1 /mnt/root
sudo mount --bind /dev /mnt/root/dev
sudo mount --bind /proc /mnt/root/proc
sudo mount --bind /sys /mnt/root/sys
sudo mount --bind /run /mnt/root/run
sudo chroot /mnt/root

Now you’re “inside” your broken system as root → run:

chown root:root /usr/bin/sudo
chmod 4755 /usr/bin/sudo
exit

Reboot without the USB.

Extra Checks After Fix

Run ls -l /usr/bin/sudo → should show -rwsr-xr-x root root
If error mentions /usr/local/bin/sudo instead: remove it (it’s overriding the real one):
```
sudo rm /usr/local/bin/sudo
hash -r   # refresh shell cache
```

Reinstall sudo package if still weird:

sudo apt update
sudo apt install --reinstall sudo

This almost always fixes it. If you get a different error or it still fails, tell me what exactly happens (and your Ubuntu version if you know it).

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