Oracle Linux: CVE-2019-17563: ELSA-2020-4004: tomcat security and bug fix update (IMPORTANT) (Multiple Advisories)

When using FORM authentication with Apache Tomcat 9.0.0.M1 to 9.0.29, 8.5.0 to 8.5.49 and 7.0.0 to 7.0.98 there was a narrow window where an attacker could perform a session fixation attack. The window was considered too narrow for an exploit to be practical but, erring on the side of caution, this issue has been treated as a security vulnerability.
It was found that tomcat's FORM authentication allowed a very small period in which an attacker could possibly force a victim to use a valid user session, or Session Fixation. While practical exploit of this issue is deemed highly improbable, an abundance of caution merits it be considered a flaw. The highest threat from this vulnerability is to system availability, but also threatens data confidentiality and integrity.