CVE-2026-28405 HIGH

CVE-2026-28405: MarkUs: Stored XSS in Submission HTML Preview Enables Instructor-Context Actions

Vendor Markusproject
Product Markus
Weakness CWE-79 · XSS
Published March 5, 2026
Last update March 6, 2026
View on NVD All CVEs

CVSS base score

8.0/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction Required
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

What the vulnerability does

01Description

MarkUs is a web application for the submission and grading of student assignments. Prior to version 2.9.1, the courses/<:course_id>/assignments/<:assignment_id>/submissions/html_content route reads the contents of a student-submitted file and renders them without sanitization. This issue has been patched in version 2.9.1.

Key dates

02Disclosure timeline

March 5, 2026 CVE published
March 6, 2026 Record updated