diff --git a/native/mod_manager/mod_manager.c b/native/mod_manager/mod_manager.c
index ce027e8..3598c04 100644
--- a/native/mod_manager/mod_manager.c
+++ b/native/mod_manager/mod_manager.c
@@ -644,6 +644,11 @@ static char **process_buff(request_rec *r, char *buff)
     ptr[i+1] = NULL;
     i = 1;
     for (; *s != '\0'; s++) {
+        /* from ap_escape_html2() */
+        if (s[i] == '<' || s[i] == '>' || s[i] == '"')
+            return NULL;
+        if (!apr_isascii(s[i]))
+            return NULL;
         if (*s == '&' || *s == '=') {
             *s = '\0';
             ptr[i] = s + 1;