Rafid Aslam

**Name of the Vulnerable Software and Affected Versions** Zulip server versions prior to 1.4.3 **Description** The issue is related to an error in the implementation of an autosubscribe feature in the check stream exists route, allowing an authenticated user to subscribe to a private stream without an invitation from an existing member. **Recommendations** For versions prior to 1.4.3, update to version 1.4.3 or later to resolve the issue.