CVE-2020-16969: Microsoft Exchange Server

High severity, CVSS 7.1. EPSS: 2.7% chance of exploitation in the next 30 days.

<p>An information disclosure vulnerability exists in how Microsoft Exchange validates tokens when handling certain messages. An attacker who successfully exploited the vulnerability could use this to gain further information from a user.</p> <p>To exploit the vulnerability, an attacker could include specially crafted OWA messages that could be loaded, without warning or filtering, from the attacker-controlled URL. This callback vector provides an information disclosure tactic used in web beacons and other types of tracking systems.</p> <p>The security update corrects the way that Exchange handles these token validations.</p>

Affected products

• Microsoft Exchange Server: version 2013 only; version 2016 only; version 2019 only

Published 2020-10-16. Last modified 2026-06-17.