# CVE-2026-35403: LORIS has potential cross-site scripting in survey_accounts module

> Attackers can execute arbitrary scripts in victim browsers via invalid visit labels due to missing Content-Type headers in LORIS.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 8 Apr 2026
- **Updated:** 10 Apr 2026
- **Also known as:** GHSA-776p-5pwh-vc8p

## What is CVE-2026-35403?

CVE-2026-35403 is a medium-severity cross-site scripting vulnerability in aces Loris, published on 8 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### 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 15.10 to before 27.0.3 and 28.0.1, there is a potential for a cross-site scripting attack in the survey_accounts module if a user provides an invalid visit label. While the data is properly JSON encoded, the Content-Type header is not set causing the web browser to interpret the payload as HTML, opening the possibility of a cross-site scripting if a user is tricked into following an invalid link. This vulnerability is fixed in 27.0.3 and 28.0.1.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-35403?

It affects 1 product.


Products: Mcgill Loris.

## How do I fix CVE-2026-35403?

No fix has been published for CVE-2026-35403 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-35403 being exploited?

There is no known exploitation of CVE-2026-35403 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-2026-35403 and fix it if it is affected.

What it is: CVE-2026-35403 is a medium-severity cross-site scripting vulnerability in aces Loris, published on 8 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-35403 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-2026-35403/ (Markdown: https://insights.sbomify.com/CVE-2026-35403/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-35403
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-35403
- OSV: https://osv.dev/vulnerability/CVE-2026-35403

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-35403/
Summaries are generated and may contain mistakes; the official description above is the record.