CVE-2021-21016 is a critical-severity (CVSS 9.1) OS Command Injection vulnerability in magento/community-edition. A fix is available for magento/community-edition — see the affected versions and patch details below.
Magento OS command injection via the WebAPI
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2021-21016 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
magento/community-edition🐘magento/community-edition🐘magento/project-community-editionReal-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
Magento versions 2.4.1 (and earlier), 2.4.0-p1 (and earlier) and 2.3.6 (and earlier) are vulnerable to OS command injection via the WebAPI. Successful exploitation could lead to remote code execution by an authenticated attacker. Access to the admin console is required for successful exploitation.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | magento/community-edition | all versions | 2.3.6-p1composer require magento/community-edition:^2.3.6-p1 |
| 🐘Packagist | magento/community-edition | ≥ 2.4.0&&< 2.4.2 | 2.4.2composer require magento/community-edition:^2.4.2 |
| 🐘Packagist | magento/project-community-edition | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for magento/community-edition, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update magento/community-edition to 2.3.6-p1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21016 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-21016 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-21016. 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-2021-21016 in your dependencies?
O3 Security finds CVE-2021-21016 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.