CVE-2026-88002

Name of the Vulnerable Software and Affected Versions Open WebUI versions 0.5.0 through 0.11.0

Description A flaw exists in the message-chain reconstruction helper located in backend/open webui/utils/misc.py. The system reconstructs chat history by map key but tracks visited entries using an optional id field within the message body. An authenticated user with a default role can store messages that omit the id field and reference each other in a parent cycle. This triggers a non-terminating walk that blocks the asyncio event loop, causing a denial of service for all users, including access to the /health endpoint and administrator functions. The process consumes excessive CPU and memory, potentially leading to an out-of-memory kill. Because the malformed chat is persisted in the database, the issue remains active across process restarts until the specific chat is deleted. The vulnerability can be triggered via the POST /api/v1/chats/new endpoint to store the malformed chat and subsequently via GET /api/v1/chats/stats/usage to trigger the infinite loop.

Recommendations Update Open WebUI to version 0.11.1.