CVE-2026-88000

Open WebUI, a widely used self-hosted AI platform, contains an infinite-loop flaw (CWE-835) in the message-deletion code path of versions 0.10.0 through 0.11.0. The DELETE /api/v1/chats/{id}/messages/{message_id} endpoint recursively follows a message's childrenIds without tracking already-visited message IDs, so an authenticated user who first saves a chat tree containing a cycle and then deletes one of its messages can hang the server's synchronous request loop indefinitely. This blocks every user's requests on that instance until the process is manually killed, making it a denial-of-service issue only, with no impact on confidentiality or integrity. The flaw is fixed in version 0.11.1, and the vendor's GitHub security advisory and fix pull request are public, but no exploitation in the wild is known and EPSS puts 30-day exploitation probability at just 0.3%.

What to do: Upgrade Open WebUI to version 0.11.1 or later, which records visited message IDs during chat-tree deletion. If immediate patching is not possible, restrict who can authenticate and create/delete chats (the attack requires a low-privileged authenticated account), and monitor for unresponsive workers or hung DELETE requests, restarting the process to recover. Check server logs for the vulnerable versions 0.10.0–0.11.0 and confirm no abnormal message-tree structures were saved by untrusted users.