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.
CVE-2026-45398
HIGHNVD 7.57.5—Elevated
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 75% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.5Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EPSS
- 25.0%
- KEV
- Not listed
Published
May 15, 2026
Last Modified
May 19, 2026
Advisory Details (3)
Auto-updated May 18, 2026🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available
IDOR: Retrieval API Bypasses Knowledge Base Access Controls · Advisory · open-webui/open-webui · GitHub
https://github.com/open-webui/open-webui/security/advisories/GHSA-4g37-7p2c-38r9generic
Release v0.9.5 · open-webui/open-webui · GitHub
https://github.com/open-webui/open-webui/releases/tag/v0.9.5generic
fix: enforce ownership check on user-memory collection queries by Classic298 · Pull Request #22109 · open-webui/open-webui · GitHub
https://github.com/open-webui/open-webui/pull/22109Vendor Advisories for CVE-2026-45398(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Frequently asked(5)
What is CVE-2026-45398?
CVE-2026-45398 is a high vulnerability published on May 15, 2026. Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.5, validatecollection_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…
When was CVE-2026-45398 disclosed?
CVE-2026-45398 was first published in the National Vulnerability Database on May 15, 2026, with the most recent update on May 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45398 actively exploited?
CVE-2026-45398 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 25.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-45398?
CVE-2026-45398 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-45398?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45398, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-45398
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