scp currently implements local-to-local copy by constructing a command line
using 'cp' in a string and then using system(). It has the problem that the file
name is exposed twice to shell expansion. The file name could contain characters
which need quoting, like $ or spaces. This second expansion must be avoided.

Steps to Reproduce:
1.touch foo\ bar
2.mkdir somedir
3.scp foo\ bar somedir
  
Actual results:
cp: cannot stat `foo': No such file or directory
cp: cannot stat `bar': No such file or directory

This can be even a security issue although with a fairly low severity:
bress@link:/tmp/josh% ls -l
total 4
drwxrwxr-x  2 bress bress 4096 Sep 19 14:51 a
-rw-rw-r--  1 bress bress    0 Sep 19 14:51 `touch feh`
bress@link:/tmp/josh% scp * a
cp: omitting directory `a'
cp: missing destination file
Try `cp --help' for more information.
zsh: exit 1     scp * a
bress@link:/tmp/josh% ls -l
total 4
drwxrwxr-x  2 bress bress 4096 Sep 19 14:51 a
-rw-rw-r--  1 bress bress    0 Sep 19 14:52 feh
-rw-rw-r--  1 bress bress    0 Sep 19 14:51 `touch feh`

Proposed solution: replace system() with fork+exec()

I'll attach a patch later.