Redis is an in-memory database that persists on disk. Prior to versions 6.2.7 and 7.0.0 an attacker attempting to load a specially crafted Lua script can cause NULL pointer dereference which will result with a crash of the redis-server process. The problem is fixed in Redis versions 7.0.0 and 6.2.7. An additional workaround to mitigate this problem without patching the redis-server executable if Lua scripting is not being used is to block access to `SCRIPT LOAD` and `EVAL` commands using ACL rules.