Sendio before 7.2.4 includes the session identifier in URLs in emails, which allows remote attackers to obtain sensitive information and hijack sessions by reading the jsessionid parameter in the Referrer HTTP header.

The Web interface in Sendio before 7.2.4 does not properly handle sessions, which allows remote authenticated users to obtain sensitive information from other users' sessions via a large number of requests.

Sendio versions before 8.2.1 were affected by a Local File Inclusion vulnerability that allowed an unauthenticated, remote attacker to read potentially sensitive system files via a specially crafted URL.