Hatchet versions up to v0.86.26 are vulnerable to an OAuth state Cross-Site Request Forgery (CSRF) vulnerability. The flaw arises because the session key for OAuth state is cleared to an empty string instead of being removed after a successful OAuth callback. This allows an attacker to reuse an empty state parameter to bind a victim's authenticated session to an attacker-controlled OAuth identity, enabling login CSRF or account takeover. The vulnerability affects deployments with enabled Google, GitHub, or Slack OAuth integrations where the victim has completed at least one OAuth flow in the current session. The issue is fixed in version 0.91.1.