CVE-2026-44552

HIGH

Open WebUI: Redis Cache Keys tool_servers and terminal_servers Missing Instance Prefix Enable Cross-Instance Cache Poisoning

Title source: cna
STIX 2.1

Description

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, the tool_servers and terminal_servers keys in utils/tools.py do use a prefix. When two or more Open WebUI instances share a Redis database (a supported and documented deployment pattern, e.g., for multi-region deployments, blue-green setups, or cluster topologies), the unprefixed keys collide. An admin on Instance A writing to tool_servers overwrites the value read by Instance B — causing Instance B's users to receive Instance A's tool server configuration. This vulnerability is fixed in 0.9.0.

References (1)

Core 1
Core References

Scores

CVSS v3 8.7
EPSS 0.0004
EPSS Percentile 11.2%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-668
Status published
Products (3)
open-webui/open-webui < 0.9.0
openwebui/open_webui < 0.9.0
pypi/open-webui 0 - 0.9.0PyPI
Published May 15, 2026
Tracked Since May 16, 2026