CVE-2021-21418 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in prestashop/ps_emailsubscription. O3 Security confirms whether CVE-2021-21418 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Potential XSS injection in the newsletter conditions field
Real-World Exposure
prestashop/ps_emailsubscriptionReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
ps_emailsubscription is a newsletter subscription module for the PrestaShop platform. An employee can inject javascript in the newsletter condition field that will then be executed on the front office The issue has been fixed in 2.6.1
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | prestashop/ps_emailsubscription | all versions | 2.6.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for prestashop/ps_emailsubscription. 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 prestashop/ps_emailsubscription to 2.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21418 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-2021-21418 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-2021-21418. 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-2021-21418 in your dependencies?
O3 detects CVE-2021-21418 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.