Auth bypass in Open-Webui
CVE-2026-45398
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.5, _validate_collection_access() checks the user-memory-* and file-* collection name prefixes but does not check knowledge base collections, which use raw UUIDs as collection names. Any authenticated user who knows a private knowledge base UUID can read its content through the retrieval query endpoints, even though the knowledge API correctly denies that user access. The same gap affects the retrieval write endpoints (/process/text, /process/file, /process/files/batch, /process/web, /process/youtube), allowing an attacker to inject content into or overwrite another user's knowledge base. This vulnerability is fixed in 0.9.5.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- Open-Webui — versions < 0.9.5
- Openwebui Open Webui
Weakness classification (CWE)
References
- github.com/open-webui/open-webui/security/advisories/GHSA-4g37-7p2c-38r9 (Exploit, Mitigation, Vendor Advisory)
- github.com/open-webui/open-webui/pull/22109 (Patch, Issue Tracking)
- github.com/open-webui/open-webui/releases/tag/v0.9.5 (Release Notes)
Frequently asked questions
- What is CVE-2026-45398?
- CVE-2026-45398 is a high-severity vulnerability in Open-Webui, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 7.5/10. Published 2026-05-15.
- How severe is CVE-2026-45398?
- High severity. CVSS v3 base score is 7.5 out of 10.