Joomla! 3.9.9 Security Release announced
IGNORE THIS RELEASE WHICH CONTAINED A BUG.
INSTEAD, UPDATE YOUR WEBSITE USING JOOMLA! 3.9.10.
See the Release Notes at the link below.
About Joomla! 3.9.9
Joomla! 3.9.9 is a Security Release which addresses ONE security vulnerability.
This release also includes several improvements.
Note: when you update from an older release (say 3.9.7) to 3.9.10 then it will also address the security vulnerability addressed by Joomla! 3.9.9.
More details at the following link.
Core - Filter attribute in subform fields allows remote code execution (affecting Joomla 3.9.7 through 3.9.8)
Back up before updating is highly recommended
Protect your assets.
Perform a FULL backup of your website (database and files) BEFORE updating the Joomla! CMS and/or its extensions.