grep <2.11 is vulnerable to command execution vulnerability, and it is not possible to patch unless you build the source directly from the git repo.
ubuntu 12.04(And everything else, I would assume) uses version 2.10 of grep. it is not possible to upgrade without downloading the src and building it yourself.
perl -e 'print "x"x(2**31)' | grep x > /dev/null
This is the grep news form for this:
* Noteworthy changes in release 2.11 (2012-03-02) [stable]
** Bug fixes
grep no longer dumps core on lines whose lengths do not fit in 'int'.
(e.g., lines longer than 2 GiB on a typical 64-bit host).
Instead, grep either works as expected, or reports an error.
An error can occur if not enough main memory is available, or if the
GNU C library's regular expression functions cannot handle such long lines.
[bug present since "the beginning"]
Solution: Send out a grep update with atleast 2.11 grep from http://git.sv.gnu.org/cgit/grep.git
2.14 has already gone stable
although, i'd also point out grep 2.12 has been stable since ~August
(In reply to comment #1)
> 2.14 has already gone stable
Yes. The purpose of the bugreport is to track the issue and to send the glsa.
@security, please file the request.
New GLSA request filed.
*** Bug 448708 has been marked as a duplicate of this bug. ***
Multiple integer overflows in GNU Grep before 2.11 might allow
context-dependent attackers to execute arbitrary code via vectors involving
a long input line that triggers a heap-based buffer overflow.
This issue was resolved and addressed in
GLSA 201403-07 at http://security.gentoo.org/glsa/glsa-201403-07.xml
by GLSA coordinator Mikle Kolyada (Zlogene).