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HIGHCVE-2026-28405Published Modified CNA GitHub_M

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

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.

Metrics

CVSS v3.1
8.0
Severity
HIGH
Fixed in
—
Affected Products
1
Affected packages
  • MarkUsProject / Markus
    < 2.9.1
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
References
CVE-2026-28405: MarkUs: Stored XSS in Submission HTML Preview Enables Instructor-Context Actions | HarborGuard CVE