“Plugin closed” means the plugin is no longer available for download or update on wordpress.org. It is not actively maintained there.
Anyone can publish a free plugin on wordpress.org. Over time, many plugins stop getting updates. Some remain usable. Others include confirmed security issues and should not stay on a live site.
When researchers report serious problems, the WordPress team may close the plugin. The directory page can remain for history, but you can no longer download it.
Example of a plugin that has been closed on wordpress.org
If a plugin on your site is closed, remove it as soon as you can. If it provides an important feature, find a maintained alternative before you delete it. Keeping a closed plugin active is a bad idea.
Security Ninja’s vulnerability scanner can also flag discontinued or vulnerable plugins from its known-issue data. Treat those alerts as a cue to update or replace.
