CVE-2019-20174
MEDIUMCVE-2019-20174 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in auth0-lock. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2019-20174 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
auth0-lock vulnerable to XSS via unsanitized placeholder property
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.
auth0-locknpmDescription
Auth0 Lock before 11.21.0 allows XSS when additionalSignUpFields is used with an untrusted placeholder.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | auth0-lock | all versions | 11.21.0 |
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 auth0-lock. 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 auth0-lock to 11.21.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-20174 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-2019-20174 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-2019-20174. 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-2019-20174 in your dependencies?
O3 detects CVE-2019-20174 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.