diff --git a/webmails/snuffleupagus.rules b/webmails/snuffleupagus.rules
index 35f0b7ce..f85b7fe4 100644
--- a/webmails/snuffleupagus.rules
+++ b/webmails/snuffleupagus.rules
@@ -124,3 +124,5 @@ sp.auto_cookie_secure.enable();
 sp.cookie.name("roundcube_sessauth").samesite("strict");
 sp.cookie.name("roundcube_sessid").samesite("strict");
 sp.ini_protection.policy_silent_fail();
+
+sp.disable_function.function("unserialize").param("data").value_r("[cCoO]:\d+:\"").drop();