CVE-2021-41243 is a high-severity (CVSS 8.8) OS Command Injection vulnerability in baserproject/basercms. O3 Security confirms whether CVE-2021-41243 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
OS Command Injection Vulnerability and Potential Zip Slip Vulnerability in baserCMS
Real-World Exposure
baserproject/basercmsReal-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
There is a Potential Zip Slip Vulnerability and OS Command Injection Vulnerability on the management system of baserCMS. Users with permissions to upload files may upload crafted zip files which may execute arbitrary commands on the host operating system. This is a vulnerability that needs to be addressed when the management system is used by an unspecified number of users. If you are eligible, please update to the new version as soon as possible.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | baserproject/basercms | all versions | 4.5.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for baserproject/basercms. 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 baserproject/basercms to 4.5.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41243 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-2021-41243 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-2021-41243. 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-2021-41243 in your dependencies?
O3 detects CVE-2021-41243 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.