# CVE-2026-42277: Onyx: IDOR in /chat/file/{file_id} allows any authenticated user to download other users files

> Authenticated users can download other users' files by guessing UUIDs due to missing ownership checks in the file download endpoint.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 May 2026
- **Updated:** 8 May 2026
- **Also known as:** GHSA-vg3h-35f7-7w6r

## What is CVE-2026-42277?

CVE-2026-42277 is a medium-severity missing authorization vulnerability in onyx-dot-app onyx, published on 8 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Onyx is an open-source AI platform. Prior to versions 3.0.9, 3.1.6, and 3.2.6, the GET /chat/file/{file_id} endpoint allows any authenticated user to download any other user's uploaded files by providing the file UUID. The endpoint verifies the caller is authenticated but never checks that the file belongs to them. An attacker who knows or obtains a file UUID can access confidential documents, chat attachments, and other files uploaded by any user in the system. This issue has been patched in versions 3.0.9, 3.1.6, and 3.2.6.

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

## Which versions are affected by CVE-2026-42277?

It affects 1 product.


Products: Onyx Onyx.

## How do I fix CVE-2026-42277?

No fix has been published for CVE-2026-42277 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-42277 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42277 exists.

## Other vulnerabilities in onyx-dot-app onyx

- [CVE-2024-7767](https://insights.sbomify.com/CVE-2024-7767/): Improper Access Control in danswer-ai/danswer (medium 6.5)
- [CVE-2024-9612](https://insights.sbomify.com/CVE-2024-9612/): Unauthorized Access in danswer-ai/danswer (medium 6.5)
- [CVE-2025-51479](https://insights.sbomify.com/CVE-2025-51479/): Missing authorization in n/a (medium 5.4)
- [CVE-2025-7894](https://insights.sbomify.com/CVE-2025-7894/): Onyx Chat Interface a3_generate_simple_sql.py generate_simple_sql sql injection (medium 5.3)
- [CVE-2026-42276](https://insights.sbomify.com/CVE-2026-42276/): Onyx: IDOR in /chat/stop-chat-session allows any authenticated user to interrupt other users chat sessions (medium 4.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42277 and fix it if it is affected.

What it is: CVE-2026-42277 is a medium-severity missing authorization vulnerability in onyx-dot-app onyx, published on 8 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-2026-42277 exists.

Affected product: onyx-dot-app onyx. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-42277/ (Markdown: https://insights.sbomify.com/CVE-2026-42277/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42277
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42277
- OSV: https://osv.dev/vulnerability/CVE-2026-42277

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42277/
Summaries are generated and may contain mistakes; the official description above is the record.