CVE-2026-28405
MarkUs: Stored XSS in Submission HTML Preview Enables Instructor-Context Actions
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.
INFO
Published Date :
March 5, 2026, 9:16 p.m.
Last Modified :
March 10, 2026, 7:53 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update MarkUs to version 2.9.1 or later.
- Review application security for file rendering.
- Sanitize all user-submitted content before rendering.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-28405.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-28405 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-28405
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-28405 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-28405 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Mar. 10, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:markusproject:markus:*:*:*:*:*:*:*:* versions up to (excluding) 2.9.1 Added Reference Type GitHub, Inc.: https://github.com/MarkUsProject/Markus/commit/55d74f2ddb72d2ec2f29aa2b4cb6b2da10755036 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/MarkUsProject/Markus/releases/tag/v2.9.1 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/MarkUsProject/Markus/security/advisories/GHSA-p5pc-pxrj-3893 Types: Vendor Advisory -
New CVE Received by [email protected]
Mar. 05, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H Added CWE CWE-79 Added Reference https://github.com/MarkUsProject/Markus/commit/55d74f2ddb72d2ec2f29aa2b4cb6b2da10755036 Added Reference https://github.com/MarkUsProject/Markus/releases/tag/v2.9.1 Added Reference https://github.com/MarkUsProject/Markus/security/advisories/GHSA-p5pc-pxrj-3893