Executive brief
Heym is a workflow automation platform. This advisory covers five independent vulnerabilities affecting versions before 0.0.53: unauthenticated webhook triggers, insecure OAuth handling, plaintext token storage, and Python code execution in workflow conditions. Attackers can execute arbitrary code as the backend user, hijack webhook authentication to trigger workflows with owner privileges, intercept OAuth tokens via malicious redirects, or exploit database leaks to obtain long-lived access tokens.
Technical details
The workflow condition evaluator uses unsafe Python eval() without effective sandboxing (CWE-94), reachable by any user editing workflow conditions. Slack and Telegram webhook signature verification fails open when credentials or secrets are absent (CWE-287), allowing unauthenticated trigger activation. OAuth redirect_uri scheme validation is missing (CWE-601), permitting javascript: and data: URIs that intercept authorization codes and execute XSS in the Heym origin. Bearer tokens (WorkflowExecutionToken, PortalSession, HITLRequest.public_token, OAuthAuthorizationCode) are stored in plaintext (CWE-312), exposing valid scoped tokens with 168-hour TTL via database compromise.
Affected products
- heymrun Heym before 0.0.53
Timeline
- 2026-09-27: disclosed
- 2026-09-27: patched: version 0.0.53