# CVE-2026-45398: Open WebUI: IDOR - Retrieval API Bypasses Knowledge Base Access Controls

> Authenticated users can read or modify private knowledge bases by bypassing access controls in retrieval APIs.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 May 2026
- **Updated:** 19 May 2026
- **Also known as:** GHSA-4g37-7p2c-38r9, PYSEC-2026-2699

## What is CVE-2026-45398?

CVE-2026-45398 is a high-severity missing authorization vulnerability in Openwebui Open Webui, published on 15 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-45398?

3 open source packages ship an affected version, including open-webui. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `open-webui` | PyPI | All versions | 0.9.5 |
| `open-webui` | PyPI | All versions | 0.9.5 |
| `open-webui` | PyPI | All versions | 0.9.5 |

Products: Openwebui Open Webui.

## How do I fix CVE-2026-45398?

Upgrade open-webui to 0.9.5 or later.

## Is CVE-2026-45398 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45398 exists.

## Other vulnerabilities in Openwebui Open Webui

- [CVE-2026-44551](https://insights.sbomify.com/CVE-2026-44551/): Open WebUI: LDAP Empty Password Authentication Bypass (critical 9.1)
- [CVE-2026-56400](https://insights.sbomify.com/CVE-2026-56400/): open-webui - Remote Code Execution via CORS Misconfiguration and Session Validation (critical 9.0)
- [CVE-2024-8017](https://insights.sbomify.com/CVE-2024-8017/): Cross-site Scripting (XSS) in open-webui/open-webui (critical 9.0)
- [CVE-2026-45672](https://insights.sbomify.com/CVE-2026-45672/): Open WebUI: Jupyter code execution works despite `ENABLE_CODE_EXECUTION=false` — feature gate bypassed (high 8.8)
- [CVE-2026-87995](https://insights.sbomify.com/CVE-2026-87995/): Open WebUI: Same-origin XSS to account takeover via terminal port-preview iframe hardcoding allow-same-origin (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45398 and fix it if it is affected.

What it is: CVE-2026-45398 is a high-severity missing authorization vulnerability in Openwebui Open Webui, published on 15 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45398 exists.

Affected packages and fixed versions:
- open-webui (PyPI): affected all versions; fixed in 0.9.5
- open-webui (PyPI): affected all versions; fixed in 0.9.5
- open-webui (PyPI): affected all versions; fixed in 0.9.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-45398/ (Markdown: https://insights.sbomify.com/CVE-2026-45398/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45398
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45398
- OSV: https://osv.dev/vulnerability/CVE-2026-45398

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45398/
Summaries are generated and may contain mistakes; the official description above is the record.