MarkUs: Stored XSS in Submission HTML Preview Enables Instructor-Context Actions
Priority LOW 36CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.
Summary
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 it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0026 17th percentileScored 2026-11-07
Fix Fixed Markus (MarkUsProject): 2.9.1
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| MarkUsProject | Markus | before 2.9.1 | 2.9.1 | Patch available | CNA |
- Markus VendorMarkUsProject Affected before 2.9.1 Fixed in 2.9.1 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:markusproject:markus:*:*:*:*:*:*:*:* | before 2.9.1 | Vulnerable | MarkUsProject |
- cpe:2.3:a:markusproject:markus:*:*:*:*:*:*:*:* Versions before 2.9.1 Vulnerable ·MarkUsProject
Remediation
- Fix · CNA Markus (MarkUsProject) Fixed in 2.9.1
Timeline
- 2026-10-02 Threatist record created from CVE-2026-28405
References
More MarkUsProject Markus vulnerabilities
- TI-2026-20241 Zip Slip in MarkUs config upload allowing RCE CVSS 3.1CRITICAL 9.1
- TI-2024-34648 Arbitrary File Write leading up to remote code execution (instructor accounts) CVSS 4.0HIGH 7.1
- TI-2024-34420 MarkUs Arbitrary File Write leading up to remote code execution (student accounts) CVSS 4.0HIGH 7.1
- TI-2026-20987 MarkUs: Zip bomb in config upload enables DoS CVSS 3.1MEDIUM 6.5
- TI-2026-20085 MarkUs has a submission-view IDOR exposes all student submissions CVSS 3.1MEDIUM 6.5
- TI-2024-32087 MarkUs vulnerable to Path Traversal CVSS 3.1MEDIUM 5.7
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences