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

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.

Published: 2026-04-08 Last update: 2026-04-21 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-35403 is rated Low Risk (29.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.03%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-35403

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-09 — 0.03% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-35403

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 1.3 4.7 [email protected]
5.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.3 2.7 [email protected]

Weakness enumeration for CVE-2026-35403

Affected software / configurations for CVE-2026-35403

Vendor Product Version Raw CPE
mcgill loris >= 15.10, <= 27.0.2 cpe:2.3:a:mcgill:loris:*:*:*:*:*:*:*:*
mcgill loris 28.0.0 cpe:2.3:a:mcgill:loris:28.0.0:*:*:*:*:*:*:*

References for CVE-2026-35403

cvelogic Threat Intelligence