How about /home/bla/public_html/blabla and /home/bla/public_html? Also, group membership does not mean that the user will have proper permissions. See also if there are ACL entries and what the group permissions are on each of the directories.

Are CGI scripts running with suEXEC permissions to a different user?

It might help to diagnose this if you were to show us what the process entry looks like for the script that is misbehaving, what the directory entries between /home/blah and /home/blah/public_html/blabla look like, and anything else that may be pertinent. With what you have provided, the best we can do is like throwing darts at a target while being blindfolded.

Thanks for pointing me to suexec. I am not very sure if I did the right thing but disabling suexec (renaming it and restart the server) seems to solve the problem :))

Note that permissions on all of the ancestor directories also matter.

To aid in diagnosing the problem, you might want to do something like the following:

my $dir = '/home/bla­/public_ht­ml/blabla'­;
my $isDir = -d $dir;
if(  $isDir  ) {
    print "Found directory: $dir\n";
} elsif(  defined $isDir  ) {
    print "Found non-directory: $dir\n";
} else {
    print "Can't stat($dir): $!\n";
}
[download]

That way you can distinguish between "permission denied" vs "no such file/dir" vs something more exotic. The next step narrows down the source of the problem:

use File::Basename 'dirname';
my $dir = '/home/bla­/public_ht­ml/blabla'­;
my $isDir;
while(  ! defined $isDir  ) {
    my $isDir = -d $dir;
    if(  $isDir  ) {
        print "Found directory: $dir\n";
    } elsif(  defined $isDir  ) {
        print "Found non-directory: $dir\n";
    } else {
        print "Can't stat($dir): $!\n";
    }
    last
        if  '/' eq $dir;
    $dir = dirname( $dir );
}
[download]

I have a question, is 0xAD part of your $dir?

I see

00000030: 62 6C 61 AD 2F 70 75 62 - 6C 69 63 5F 68 74 AD 6D |bla /publ
+ic_ht m|
[download]