Only the latest release receives security fixes.

Do not open a public issue for security vulnerabilities.

Report privately via GitHub's Security Advisories feature.

Include:

• A clear description of the vulnerability
• Steps to reproduce
• Potential impact (e.g. command injection, privilege escalation, crash)
• Affected version(s)

You can expect an initial response within 72 hours and a patch within 14 days for confirmed critical issues.

GUI API runs entirely server-side. The attack surfaces to keep in mind:

GUI JSON files are loaded from the server's datapack directory. Anyone who can place files in world/datapacks/ already has filesystem access to the server — GUI API does not expand that trust boundary.

Buttons with "run_with": "console" execute commands with server-level (console) permission. This is intentional and only reachable by players who trigger a button defined by the datapack author. If you expose such buttons without a condition guard, any player who opens the GUI can trigger the command.

Recommendation: Always gate elevated-command buttons with a condition such as has_tag to restrict access.

The run_command action passes the value string directly to the Minecraft command dispatcher. The value is set at datapack authoring time — it is not interpolated with player input at runtime. There is no runtime injection surface from the player side.

All slot interactions inside a GUI inventory are consumed server-side. quickMove (shift-drag), THROW (Q), CLONE (middle-click), and all other SlotActionType variants other than PICKUP and QUICK_MOVE are silently discarded, preventing item duplication or extraction.

Per-player open state is stored in a server-side HashMap<UUID, OpenState>. It is cleared on screen close. There is no persistent state across sessions, no serialisation to disk, and no cross-player data sharing.

• Client-side spoofing of slot clicks — the server validates all slot interactions before acting. Clients cannot trigger actions on slots that have no button defined.
• Permission escalation via /guiapi open — the command requires permission level 2. Players cannot open GUIs for other players without OP.