CVE-2026-28405: high-severity vulnerability in MarkUsProject Markus
MarkUs: Stored XSS in Submission HTML Preview Enables Instructor-Context Actions
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8epss 0.3%
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.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
Affected products
MarkUsProject · MarkusRelated CVEs — MarkUsProject Markus
In the same product, most dangerous first.
CVE-2024-47820MEDIUMMarkUs vulnerable to Path TraversalEPSS 0.7%CVE-2024-51743HIGHArbitrary File Write leading up to remote code execution (instructor accounts)EPSS 0.7%CVE-2024-51499HIGHMarkUs Arbitrary File Write leading up to remote code execution (student accounts)EPSS 0.7%CVE-2026-25057CRITICALZip Slip in MarkUs config upload allowing RCEEPSS 0.5%CVE-2026-27807MEDIUMMarkUs: YAML alias (‘billion laughs’) DoS in config uploadEPSS 0.3%CVE-2026-25962MEDIUMMarkUs: Zip bomb in config upload enables DoSEPSS 0.3%