CVE-2016-10531 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in marked. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for marked — see the affected versions and patch details below.
Sanitization bypass using HTML Entities in marked
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
markednpmDescription
Affected versions of marked are susceptible to a cross-site scripting vulnerability in link components when sanitize:true is configured.
Proof of Concept
This flaw exists because link URIs containing HTML entities get processed in an abnormal manner. Any HTML Entities get parsed on a best-effort basis and included in the resulting link, while if that parsing fails that character is omitted.
For example:
A link URI such as
javascript֍ocument;alert(1)
Renders a valid link that when clicked will execute alert(1).
Recommendation
Update to version 0.3.6 or later.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | marked | all versions | 0.3.6npm install marked@0.3.6 |
Affected Products
markedmarked_projectResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for marked, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update marked to 0.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-10531 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2016-10531 in your dependencies?
Find it across npm, including transitive dependencies.