Checkmk Werk 14485: Fix session cookie validation on RestAPI

ID: 14485 Title: Fix session cookie validation on RestAPI Component: REST API Level: 1 Class: Security fix Version: 2.2.0i1 Before this Werk expired sessions were still valid on the RestAPI, since the RestAPI only vaildated the Cookie signature. An attacker who was able to steal a session cookie could use that cookie on the RestAPI even after the session expired. Some actions though require access to the user session, these action fail due to the expired session. Some actions do not access the session and are therefore possible. <b>Affected Versions</b>: All versions with the RestAPI are affected: 2.0, and 2.1. <b>Mitigations</b>: Immediate mitigations are not available. <b>Indicators of Compromise</b>: Review Apache and web.log for suspicious logs. <b>Vulnerability Management</b>: We have rated the issue with a CVSS Score of 5.6 (Medium) with the following CVSS vector: <tt>CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L</tt>. A CVE has been requested.