server/action.py in Fail2ban before 0.8.8 does not properly handle the content of the matches tag, which might allow remote attackers to trigger unsafe behavior in a custom action file via unspecified symbols in this content.
lists.opensuse.org/opensuse-updates/2013-04/msg00001.html
lists.opensuse.org/opensuse-updates/2013-04/msg00002.html
sourceforge.net/mailarchive/message.php?msg_id=30193056
www.mandriva.com/security/advisories?name=MDVSA-2013:078
www.openwall.com/lists/oss-security/2012/12/17/2
bugs.gentoo.org/show_bug.cgi?id=447572
bugzilla.redhat.com/show_bug.cgi?id=887914
github.com/fail2ban/fail2ban/commit/83109bc
raw.github.com/fail2ban/fail2ban/master/ChangeLog