CVE-2016-3942 is a medium-severity (CVSS 6.3) remote code execution vulnerability in jsrender. O3 Security confirms whether CVE-2016-3942 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Template Injection in jsrender
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.
jsrendernpmDescription
Affected versions of jsrender are susceptible to a remote code execution vulnerability when used with server delivered client-side tempates which dynamically embed user input.
Proof of Concept
//POC-REQUEST
{{for ~x!=1?(constructor.constructor("return arguments.callee.caller")()):~y(10)}}
{{:#data}}
{{/for}}
//POC-RESPONSE
function anonymous(data,view,j,u) { // template var v,t=j._tag,ret="" +t("for",view,this,[ {view:view,tmpl:1, params:{args:['~x!=1?(constructor.constructor(\"return arguments.callee.caller\")()):~y(10)']}, args:[view.hlp("x")!=1?(data.constructor.constructor("return arguments.callee.caller")()):view.hlp("y")(10)], props:{}}]); return ret; }
Recommendation
Update to version 0.9.74 or later.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | jsrender | all versions | 0.9.74 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jsrender. 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 jsrender to 0.9.74 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-3942 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-2016-3942 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-2016-3942. 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-2016-3942 in your dependencies?
O3 detects CVE-2016-3942 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.