CVE-2026-35446

High

Published: 08 April 2026

Published

08 April 2026

Modified

21 April 2026

KEV Added

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Patch

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CVSS Score 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

EPSS Score 0.0004 12.6th percentile

Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-35446 is a high-severity Files or Directories Accessible to External Parties (CWE-552) vulnerability in Mcgill Loris. Its CVSS base score is 7.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 12.6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and SI-10 (Information Input Validation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

Directly mitigates the directory traversal vulnerability by identifying, reporting, and applying the vendor patches released in LORIS versions 27.0.3 and 28.0.1.

SI-10 Information Input Validation good match

prevent

Validates and sanitizes file path inputs to the FilesDownloadHandler, preventing attackers from using traversal sequences like '../' to escape intended directories.

AC-3 Access Enforcement good match

prevent

Enforces logical access restrictions in the application to ensure low-privilege users can only access files within authorized download directories.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1005 Data from Local System Collection

Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.

attack.mitre.org →

Why these techniques?

Directory traversal in the LORIS web app's download handler directly enables exploitation of a public-facing application (T1190) to read arbitrary sensitive files on the local system (T1005).

Confidence: MEDIUM · MITRE ATT&CK Enterprise v18.1

NVD Description

LORIS (Longitudinal Online Research and Imaging System) is a self-hosted web application that provides data- and project-management for neuroimaging research. From 24.0.0 to before 27.0.3 and 28.0.1, an incorrect order of operations in the FilesDownloadHandler could result in an attacker…

escaping the intended download directories. This vulnerability is fixed in 27.0.3 and 28.0.1.

Deeper analysisAI

CVE-2026-35446 is a directory traversal vulnerability in LORIS, a self-hosted web application for data and project management in neuroimaging research. The issue stems from an incorrect order of operations in the FilesDownloadHandler, affecting versions from 24.0.0 up to but not including 27.0.3 and 28.0.1. This flaw, classified under CWE-552 (Files or Directories Accessible to External Parties), carries a CVSS v3.1 base score of 7.7 (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N), indicating high severity due to its potential for unauthorized data access.

An attacker with low-privilege authenticated access (PR:L) can exploit this vulnerability over the network (AV:N) with low complexity (AC:L) and no user interaction required (UI:N). By manipulating download requests, they can escape the intended download directories, achieving high-impact confidentiality breaches (C:H) in a scoped manner (S:C), such as reading sensitive files outside the restricted paths, while integrity and availability remain unaffected.

The GitHub security advisory (GHSA-47jj-7xfg-8759) confirms the vulnerability and states it is fixed in LORIS versions 27.0.3 and 28.0.1. Security practitioners should upgrade to these patched releases to mitigate the issue, ensuring all instances of affected versions are updated promptly.