2 files changed, 7 insertions, 0 deletions
diff --git a/debian/changelog b/debian/changelog
index f78b248..f63626e 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -2,6 +2,8 @@ etckeeper (1.13) UNRELEASED; urgency=medium
 
   * Ignore check-mk-agent-logwatch's FHS violating
     /etc/check_mk/logwatch.state. Closes: #753903
+  * Only allow [-a-z_] in etckeeper commands to avoid any possible directory
+    traversal etc issues.
 
  -- Joey Hess <joeyh@debian.org>  Sat, 05 Jul 2014 19:03:00 -0400
 
diff --git a/etckeeper b/etckeeper
index 1498b96..554ada9 100755
--- a/etckeeper
+++ b/etckeeper
@@ -75,6 +75,11 @@ elif [ "$command" = "pre-apt" ]; then
 	command=pre-install
 fi
 
+if echo "$command" | egrep -q '[^-a-z_]'; then
+	echo "etckeeper: invalid command $command" >&2
+	exit 1
+fi
+
 if [ ! -d "$ETCKEEPER_CONF_DIR/$command.d" ]; then
 	echo "etckeeper: $ETCKEEPER_CONF_DIR/$command.d does not exist" >&2
 	exit 1