CVE-2026-27807 Details
Description
MarkUs is a web application for the submission and grading of student assignments. Prior to version 2.9.4, MarkUs allows course instructors to upload YAML files to create/update various entities (e.g., assignment settings). These YAML files are parsed with aliases enabled. This issue has been patched in version 2.9.4.
A denial-of-service vulnerability has been identified in MarkUs versions prior to 2.9.4. The issue arises from the application's handling of YAML files uploaded by course instructors to manage various entities, such as assignment settings. These YAML files are parsed with aliases enabled, allowing for a 'billion laughs' attack. This crafted YAML triggers exponential alias expansion, leading to excessive CPU and RAM consumption, and causing a denial-of-service condition.
Users can upgrade to MarkUs version 2.9.4 to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Mar 6, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/MarkUsProject/Markus/releases/tag/v2.9.4 | [email protected] | ProductRelease Notes |
| https://github.com/MarkUsProject/Markus/security/advisories/GHSA-m9rx-85mx-q9h6 | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-776 | Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| markusproject markus | < 2.9.4 |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Mar 12, 2026 | Initial Analysis | [email protected] |
| Mar 6, 2026 | New CVE Received | [email protected] |