What is CVE-2026-28405?

CVE-2026-28405 is a high-severity vulnerability in Markusproject Markus, classified under Cross-site Scripting. CVSS score: 8.0/10. Published 2026-03-05.

How severe is CVE-2026-28405?

High severity. CVSS v3 base score is 8.0 out of 10.

XSS in Markusproject Markus

CVE-2026-28405

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.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (13.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H.

Affected products

Markusproject Markus — versions < 2.9.1

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC, Release Notes)

Frequently asked questions

What is CVE-2026-28405?: CVE-2026-28405 is a high-severity vulnerability in Markusproject Markus, classified under Cross-site Scripting. CVSS score: 8.0/10. Published 2026-03-05.
How severe is CVE-2026-28405?: High severity. CVSS v3 base score is 8.0 out of 10.