diff --git a/dnsapi/dns_autodns.sh b/dnsapi/dns_autodns.sh
index ce566978..e26d699b 100644
--- a/dnsapi/dns_autodns.sh
+++ b/dnsapi/dns_autodns.sh
@@ -139,12 +139,21 @@ _get_autodns_zone() {
   return 1
 }
 
+# Escape the XML special characters (& < > ' ") so that credentials
+# containing them do not break the request document (issue 5317).
+_autodns_xml_encode() {
+  sed "s/&/\&amp;/g;s/</\&lt;/g;s/>/\&gt;/g;s/'/\&apos;/g;s/\"/\&quot;/g"
+}
+
 _build_request_auth_xml() {
+  _autodns_user_xml="$(printf "%s" "$AUTODNS_USER" | _autodns_xml_encode)"
+  _autodns_password_xml="$(printf "%s" "$AUTODNS_PASSWORD" | _autodns_xml_encode)"
+  _autodns_context_xml="$(printf "%s" "$AUTODNS_CONTEXT" | _autodns_xml_encode)"
   printf "<auth>
     <user>%s</user>
     <password>%s</password>
     <context>%s</context>
-  </auth>" "$AUTODNS_USER" "$AUTODNS_PASSWORD" "$AUTODNS_CONTEXT"
+  </auth>" "$_autodns_user_xml" "$_autodns_password_xml" "$_autodns_context_xml"
 }
 
 # Arguments: