CVE-2016-10531 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in marked. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2016-10531 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Sanitization bypass using HTML Entities in marked
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
markednpmDescription
marked is an application that is meant to parse and compile markdown. Due to the way that marked 0.3.5 and earlier parses input, specifically HTML entities, it's possible to bypass marked's content injection protection (sanitize: true) to inject a javascript: URL. This flaw exists because &#xNNanything; gets parsed to what it could and leaves the rest behind, resulting in just anything; being left.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | marked | all versions | 0.3.6 |
Research 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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2016-10531 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2016-10531. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2016-10531 in your dependencies?
O3 detects CVE-2016-10531 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.