CVE-2026-28405: MarkUs is a web application for the submission and grading of student assignments

Q: How do I fix CVE-2026-28405?

markus: upgrade to 2.9.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-28405 being exploited?

CVE-2026-28405 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-28405 affect?

CVE-2026-28405 affects markus. Severity is high (CVSS 8.0). 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 a

Routine

HIGH 8.0UPGRADE

CVE-2026-28405 is a high-severity flaw (CVSS 8.0) affecting markus. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.0 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.2% (top 86%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-03-05
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: markusproject

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-05 21:16 UTCPublished CVE record published
2026-06-17 10:28 UTCUpdated Record last modified

markusproject markus UPGRADE

Affected: < 2.9.1

Fixed in: 2.9.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy markus || rpm -q markus || markus --version

2. UPGRADE to 2.9.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade markus

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade markus

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-28405?

markus: upgrade to 2.9.1. Exact commands for each OS are on this page.

Is CVE-2026-28405 being exploited?

CVE-2026-28405 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-28405 affect?

CVE-2026-28405 affects markus. Severity is high (CVSS 8.0). 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 a

How urgent is CVE-2026-28405?

Priority 32/100. High severity

Related CVEs

CVE-2026-27807 MEDIUM 4.9 UPGRADE MarkUs is a web application for the submission and grading of student assignments
CVE-2026-25962 MEDIUM 6.5 UPGRADE MarkUs is a web application for the submission and grading of student assignments
CVE-2024-51743 HIGH 8.8 UPGRADE MarkUs is a web application for the submission and grading of student assignments
CVE-2024-51499 HIGH 8.8 UPGRADE MarkUs is a web application for the submission and grading of student assignments
CVE-2024-47820 MEDIUM 5.7 UPGRADE MarkUs, a web application for the submission and grading of student assignments, is vulnerable to path travers

References

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