CVE-2026-27807
MarkUs: YAML alias (‘billion laughs’) DoS in config upload
CVSS Score
4.9
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-776 |
| Vendor | markusproject |
| Product | markus |
| Published | Mar 6, 2026 |
| Last Updated | Mar 6, 2026 |
Stay Ahead of the Next One
Get instant alerts for markusproject markus
Be the first to know when new medium vulnerabilities affecting markusproject markus are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
MarkUsProject / Markus
< 2.9.4