In Zabbix 7.4 the cryptographic key used for signing Frontend sessions has been erroneously written to the database seed. Currently the only known exploitation scenario is for deployments that utilize both - SAML authentication and guest users. In such cases the key can be used to forge valid session cookies, potentially leading to unauthorized access. For other Zabbix deployments this does not have a known impact.
An unauthenticated attacker with Frontend access might be able to generate valid session cookies in certain deployments.
As a workaround, the pre-seeded session key can be manually cleared from Zabbix DB by setting value of 'settings.session_key' to an empty string. Zabbix Frontend will then generate a new random key.
Upgrade Zabbix Server to the latest version, an upgrade patch will remove the session key from the DB.