What is CVE-2026-28405?

MarkUs is a web application for the submission and grading of student assignments. Prior to version 2.9.1, the courses/ /assignments/ /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.

How severe is CVE-2026-28405?

CVE-2026-28405 has a CVSS 3.x base score of 8.0, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-28405 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-28405?

CVE-2026-28405 affects Markusproject Markus. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-28405?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-28405 have an EU (EUVD) identifier?

Yes. CVE-2026-28405 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9870.

When was CVE-2026-28405 published?

CVE-2026-28405 was published on 2026-03-05 and last updated on 2026-06-17.

CVE-2026-28405

CVE-2026-28405 is a high-severity vulnerability in Markusproject Markus with a CVSS 3.x base score of 8.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: High (CVSS 3.x base score 8.0)
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-9870
Weakness: CWE-79
Affected product: Markusproject Markus
Published: 2026-03-05
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-28405?: CVE-2026-28405 has a CVSS 3.x base score of 8.0, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-28405 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-28405?: CVE-2026-28405 affects Markusproject Markus. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-28405?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-28405 have an EU (EUVD) identifier?: Yes. CVE-2026-28405 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9870.
When was CVE-2026-28405 published?: CVE-2026-28405 was published on 2026-03-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:markusproject:markus:*:*:*:*:*:*:*:*

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