# CVE-2026-45339: Open WebUI's API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints

> Attackers can bypass API key restrictions on restricted endpoints by using the x-api-key header instead of Authorization, allowing unauthorized model invocation.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 May 2026
- **Updated:** 19 May 2026
- **Also known as:** GHSA-57q6-fvp4-pqmm, PYSEC-2026-3543

## What is CVE-2026-45339?

CVE-2026-45339 is a medium-severity authentication bypass vulnerability in Openwebui Open Webui, published on 15 May 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, Open WebUI allows admins to restrict which API endpoints an API key can access. When an API key is restricted from /api/v1/messages, requests using the Authorization: Bearer sk-... header are correctly blocked with 403. However, the same key sent via the x-api-key header bypasses the restriction entirely — the request is authenticated, the model is invoked, and a full response is returned. This vulnerability is fixed in 0.9.0.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-45339?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `open-webui` | PyPI | All versions | 0.9.0 |
| `open-webu` | PyPI | All versions | 0.9.0 |
| `open-webu` | PyPI | All versions | 0.9.0 |

Products: Openwebui Open Webui.

## How do I fix CVE-2026-45339?

Upgrade open-webui to 0.9.0 or later.

## Is CVE-2026-45339 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45339 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-2026-45339 and fix it if it is affected.

What it is: CVE-2026-45339 is a medium-severity authentication bypass vulnerability in Openwebui Open Webui, published on 15 May 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45339 exists.

Affected packages and fixed versions:
- open-webui (PyPI): affected all versions; fixed in 0.9.0
- open-webu (PyPI): affected all versions; fixed in 0.9.0
- open-webu (PyPI): affected all versions; fixed in 0.9.0

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-2026-45339/ (Markdown: https://insights.sbomify.com/CVE-2026-45339/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45339
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45339
- OSV: https://osv.dev/vulnerability/CVE-2026-45339

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45339/
Summaries are generated and may contain mistakes; the official description above is the record.