diff --git a/doc/configuration.txt b/doc/configuration.txt
index e39db29b4..f2124db95 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -18726,11 +18726,18 @@ pass-header <name> [ { if | unless } <condition> ]
   the FastCGI application because they are already converted into parameters.
 
 path-info <regex>
-  Define a regular expression to extract the script-name and the path-info
-  from the URI. Thus, <regex> should have two captures: the first one to
-  capture the script name and the second one to capture the path-info. It is an
-  optional setting. If it is not defined, no matching is performed on the
-  URI. and the FastCGI parameters PATH_INFO and PATH_TRANSLATED are not filled.
+  Define a regular expression to extract the script-name and the path-info from
+  the URL-decoded path. Thus, <regex> should have two captures: the first one
+  to capture the script name and the second one to capture the path-info. It is
+  an optional setting. If it is not defined, no matching is performed on the
+  path. and the FastCGI parameters PATH_INFO and PATH_TRANSLATED are not filled.
+
+  For security reason, when this regular expression is defined, the newline and
+  the null characters are forbiden from the path, once URL-decoded. The reason
+  to such limitation is because otherwise the matching always fails (due to a
+  limitation one the way regular expression are executed in HAProxy). So if one
+  of these two characters is found in the URL-decoded path, an error is
+  returned to the client. The principle of least astonishment is applied here.
 
   Example :
      path-info ^(/.+\.php)(/.*)?$
diff --git a/src/mux_fcgi.c b/src/mux_fcgi.c
index 38c2bfd64..12d29d686 100644
--- a/src/mux_fcgi.c
+++ b/src/mux_fcgi.c
@@ -1345,6 +1345,15 @@ static int fcgi_set_default_param(struct fcgi_conn *fconn, struct fcgi_strm *fst
 		if (!fconn->app->pathinfo_re)
 			goto check_index;
 
+		/* If some special characters are found in the decoded path (\n
+		 * or \0), the PATH_INFO regex cannot match. This is theorically
+		 * valid, but probably unexpected, to have such characters. So,
+		 * to avoid any suprises, an error is triggered in this
+		 * case.
+		 */
+		if (istchr(path, '\n') || istchr(path, '\0'))
+			goto error;
+
 		/* The regex does not match, just to the last part and see if
 		 * the index must be used.
 		 */