I accidentally ran sudo chmod -R 777 /home/

I accidentally executed:

sudo chmod -R 777 /home/

Is there any way to recover from this?

Usually yes. You can change back to default permissions of 755 (directories) and 644 (files).

But you need to set permissions for some files, e.g. files in .ssh, .gnupg or .local/bin.

# Set all files to 664, and all directories to 755
sudo find /home -type f -exec chmod 644 {} +
sudo find /home -type d -exec chmod 755 {} +

# Optional, set individual /home/ directories to private
# as it is default for Ubuntu > 21.04
sudo chmod 750 /home/*/

# Restrict .ssh directory
if [ -d ~/.ssh ]; then
    chmod 700 ~/.ssh
    find ~/.ssh -type f -exec chmod 600 {} +
fi

# Restrict .gnupg directory
if [ -d ~/.gnupg ]; then
    chmod 700 ~/.gnupg
    find ~/.gnupg -type f -exec chmod 600 {} +
fi

# Restrict access to .Xauthority
[ -f ~/.Xauthority ] && chmod 600 ~/.Xauthority

# Give +x for all files in $PATH
echo "$PATH" | tr : '\0' | grep -z '^/home' | xargs -r -0 -I{} chmod +x {}/*

• If you have more than one user, you can change permissions using sudo and /home/*/ instead of ~/.
• Note, that if you manually changed permissions of some files, you need to set this again.
• This might not be complete.