Cyber Resilience

CVE-2026-45398

HighPublic PoC

Published: 15 May 2026

Published
15 May 2026
Modified
19 May 2026
KEV Added
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Patch
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CVSS Score v3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0004 13.4th percentile
Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-45398 is a high-severity Authorization Bypass Through User-Controlled Key (CWE-639) vulnerability in Openwebui Open Webui. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 13.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

This vulnerability is AI-related — categorised as LLM Application Platforms; in the Privacy and Disclosure risk domain.

EU & UK References

Vulnerability details

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…

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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.

CWE(s)
CWE-639

AI Security AnalysisAI

AI Category
LLM Application Platforms
Risk Domain
Privacy and Disclosure
OWASP Top 10 for LLMs 2025
None mapped
Classification Reason
Matched keywords: artificial intelligence, open webui

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

Authz bypass in web app retrieval endpoints directly enables exploitation of the public/self-hosted application for unauthorized data access and manipulation.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v18.1

CVEs Like This One

CVE-2026-28788Same product: Openwebui Open Webui
CVE-2026-45671Same product: Openwebui Open Webui
CVE-2026-44567Same product: Openwebui Open Webui
CVE-2026-44551Same product: Openwebui Open Webui
CVE-2026-45400Same product: Openwebui Open Webui
CVE-2026-44570Same product: Openwebui Open Webui
CVE-2026-45350Same product: Openwebui Open Webui
CVE-2026-45349Same product: Openwebui Open Webui
CVE-2026-45331Same product: Openwebui Open Webui
CVE-2026-45338Same product: Openwebui Open Webui

Affected Assets

openwebui
open webui
≤ 0.9.5

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

AC-24 Access Control Decisions
addresses: CWE-639

Per-request decision making makes it harder to bypass authorization using user-controlled keys without proper validation in the decision process.

AC-3 Access Enforcement
addresses: CWE-639

Consistent enforcement of approved authorizations makes bypassing via user-controlled keys ineffective.

References