XSS in Aces Loris
CVE-2026-35403
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:N.
EPSS exploit prediction
EPSS: 0.002 (11.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 11th percentile — 11.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.001
Affected products
- Aces Loris — versions >= 15.10, < 27.0.3, >= 28.0.0, < 28.0.1
- Mcgill Loris — versions 28.0.0
Weakness classification (CWE)
References
- github.com/aces/Loris/security/advisories/GHSA-776p-5pwh-vc8p (Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-35403?
- CVE-2026-35403 is a medium-severity vulnerability in Aces Loris, classified under Cross-site Scripting. CVSS score: 6.5/10. Published 2026-04-08.
- How severe is CVE-2026-35403?
- Medium severity. CVSS v3 base score is 6.5 out of 10.