ONLYOFFICE all versions as of 2021-11-08 is affected by Incorrect Access Control. An attacker can authenticate with the web socket service of the ONLYOFFICE document editor which is protected by JWT auth by using a default JWT signing key.
CWE-287 - Improper Authentication
Improper (or broken) authentication attacks are widespread, and have accounted for many of the worst data breaches in recent years. Improper authentication attacks are a class of vulnerabilities where an attacker impersonates a legitimate user by exploiting weaknesses in either session management or credential management to gain access to the user’s account. This can result in disclosure of sensitive information, and can lead to system compromise, theft, identity theft, and fraud.