# CVE-2026-34985: LORIS has incorrect access checks in media module

> Attackers can access unauthorized media files in LORIS by guessing filenames, bypassing frontend filters due to missing backend access checks.

- **Severity:** Medium 6.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L`)
- **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 Apr 2026
- **Updated:** 10 Apr 2026
- **Also known as:** GHSA-p42c-4gmq-hrjw

## What is CVE-2026-34985?

CVE-2026-34985 is a medium-severity missing authorization vulnerability in aces Loris, published on 8 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

LORIS (Longitudinal Online Research and Imaging System) is a self-hosted web application that provides data- and project-management for neuroimaging research. From 16.1.0 to before 27.0.3 and 28.0.1, While the frontend of the media module filters files that the user should not have access to, the backend was not applying access checks and it would be possible for someone who should not have access to a file to access it if they know the filename. This vulnerability is fixed in 27.0.3 and 28.0.1.

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

## Which versions are affected by CVE-2026-34985?

It affects 1 product.


Products: Mcgill Loris.

## How do I fix CVE-2026-34985?

No fix has been published for CVE-2026-34985 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34985 being exploited?

There is no known exploitation of CVE-2026-34985 in the wild and no public exploit code.

## Other vulnerabilities in aces Loris

- [CVE-2026-35169](https://insights.sbomify.com/CVE-2026-35169/): LORIS has potential cross-site scripting in help_editor module (high 8.7)
- [CVE-2026-26984](https://insights.sbomify.com/CVE-2026-26984/): LORIS media module vulnerable to remote code execution (high 8.7)
- [CVE-2026-26985](https://insights.sbomify.com/CVE-2026-26985/): LORIS vulnerable to path traversal in electrophysiology_browser (high 8.1)
- [CVE-2026-35446](https://insights.sbomify.com/CVE-2026-35446/): LORIS has a path traversal in FilesDownloadHandler (high 7.7)
- [CVE-2026-33350](https://insights.sbomify.com/CVE-2026-33350/): LORIS has a SQL injection in MRI feedback popup (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34985 and fix it if it is affected.

What it is: CVE-2026-34985 is a medium-severity missing authorization vulnerability in aces Loris, published on 8 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-34985 in the wild and no public exploit code.

Affected product: aces Loris. 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-2026-34985/ (Markdown: https://insights.sbomify.com/CVE-2026-34985/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34985
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34985
- OSV: https://osv.dev/vulnerability/CVE-2026-34985

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34985/
Summaries are generated and may contain mistakes; the official description above is the record.