Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.3, the unauthenticated POST /api/v1/prediction/:id endpoint accepted an overrideConfig object and unconditionally spread it into internal flowConfig and flowData objects in packages/server/src/utils/buildChatflow.ts and packages/server/src/utils/index.ts without checking apiOverrideStatus. This allowed unauthenticated attackers to inject arbitrary properties into the flow execution context of any public chatflow, overwrite values such as chatId, sessionId, and chatHistory, and control values resolved through $flow.* template variables consumed by flow nodes. This issue is fixed in version 3.1.3.