Note this is already fixed in FC4 (since FC4-re0522.0)

+++ This bug was initially created as a clone of Bug #121514 +++

Al Viro posted to vendor-sec on Apr22:

zgrep contains the following gem:

for i do
[snip]
      if test $with_filename -eq 1; then
        sed_script="s|^[^:]*:|${i}:|"
      else
        sed_script="s|^|${i}:|"
      fi
      $grep $opt "$pat" | sed "$sed_script"
[snip]
done

Aside of the correctness issues (try to use zgrep on files with e.g.
'&' in names), it leads to obvious fun when zgrep arguments had been
obtained by globbing in an untrusted place.  Even with standard sed we
have at least ;w<filename>; to deal with; for GNU sed there's also ;e;
on top of that (execute the contents of pattern space).  bzgrep is no
better - it's based on zgrep.

AFAICS, there are two solutions - one is to do what *BSD had done and
make grep(1) use zlib and libbz; then zgrep et.al. become links to
grep.  Another is to quote \, |, ; and newlines, which means extra
invocation of sed(1)...