CVE-2018-18943 — basercms
MEDIUMCVE-2018-18943 is a medium-severity (CVSS 4.8) Cross-site Scripting (XSS) vulnerability in baserproject/basercms. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for baserproject/basercms — see the affected versions and patch details below.
XSS in baserCMS before 4.1.4
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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
An issue was discovered in baserCMS before 4.1.4. In the Register New Category feature of the Upload menu, the category name can be used for XSS via the data[UploaderCategory][name] parameter to an admin/uploader/uploader_categories/edit URI.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | baserproject/basercms | all versions | 4.1.4composer require baserproject/basercms:^4.1.4 |
Affected Products
basercmsbasercmsResearch 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 baserproject/basercms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update baserproject/basercms to 4.1.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-18943 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2018-18943 in your dependencies?
Find it across Packagist, including transitive dependencies.