CVE-2026-35403: LORIS (Longitudinal Online Research and Imaging System) is a self-hosted web application that provides data- a

Routine

MEDIUM 6.5UPGRADE

CVE-2026-35403 is a medium-severity flaw (CVSS 6.5) affecting loris. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 payloa

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.2% (top 94%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-04-08
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: mcgill

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-08 19:25 UTCPublished CVE record published
2026-07-24 21:10 UTCUpdated Record last modified

mcgill loris UPGRADE

Affected: >= 15.10 and <= 27.0.2 · 28.0.0

Fixed in: newer than 27.0.2

Safe to downgrade to: a release before 15.10

1. Check installed version

apt-cache policy loris || rpm -q loris || loris --version

2. UPGRADE to newer than 27.0.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade loris

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade loris

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 15.10 (Debian / Ubuntu)

apt-cache madison loris sudo apt install loris=<VERSION_BEFORE_15.10> sudo apt-mark hold loris

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list loris sudo dnf downgrade loris-<VERSION_BEFORE_15.10> sudo dnf versionlock add loris

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-35403?

loris: upgrade to newer than 27.0.2. Exact commands for each OS are on this page.

Is CVE-2026-35403 being exploited?

CVE-2026-35403 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-35403 affect?

CVE-2026-35403 affects loris. Severity is medium (CVSS 6.5). 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 scr

How urgent is CVE-2026-35403?

Priority 24/100. No elevated risk signals yet.

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References

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