Heym before version 0.0.53 suffers from several distinct security issues: (1) The workflow condition evaluator uses Python's eval() without sandboxing, enabling arbitrary code execution by users who can edit workflow nodes or import malicious templates. (2) Slack and Telegram webhook signature verifications fail open if credentials or secrets are missing, allowing unauthenticated triggering of workflows with owner credentials. (3) The OAuth authorization endpoint does not validate the redirect_uri scheme, permitting attackers to register clients with javascript: or data: URIs and execute attacker-controlled JavaScript in Heym's origin, accessing HttpOnly cookies. (4) Sensitive tokens including WorkflowExecutionToken, PortalSession, HITLRequest.public_token, and OAuthAuthorizationCode are stored in plaintext in the database, exposing valid bearer tokens with long TTLs if the database is compromised.

Successful exploitation can lead to remote arbitrary code execution on the backend process, unauthorized triggering of workflows with owner privileges, cross-site scripting attacks that compromise user sessions, and theft of long-lived bearer tokens from database exposure. This can result in full compromise of the affected Heym instance and its workflows.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict access to workflow editing and template import features to trusted users only, ensure webhook credentials and secrets are properly configured, and protect database access to prevent token exposure.