CVE-2026-28405
MarkUs: Stored XSS in Submission HTML Preview Enables Instructor-Context Actions
CVSS Score
8.0
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-79 |
| Vendor | markusproject |
| Product | markus |
| Published | Mar 5, 2026 |
| Last Updated | Mar 6, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
MarkUsProject / Markus
< 2.9.1