Open Source Matters · Joomla! · CVE-2016-9838
**Name of the Vulnerable Software and Affected Versions**
Joomla! versions prior to 3.6.5
**Description**
An issue was discovered in the registration model of Joomla!, where incorrect filtering of registration form data stored in the session on a validation error allows a user to gain access to a registered user's account. This enables the attacker to reset the user's group mappings, username, and password by submitting a form that targets the `registration.register` task.
**Recommendations**
For versions prior to 3.6.5, update to version 3.6.5 or later to resolve the issue.