GHSA-r7q4-cw9r-vhp4
LOWConcrete CMS Stored XSS in the Custom Class page editing
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.
Blast Radius
concrete5/concrete5🐘concrete5/concrete5Real-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
Concrete CMS version 9 before 9.2.8 and previous versions before 8.5.16 are vulnerable to Stored XSS in the Custom Class page editing. Prior to the fix, a rogue administrator could insert malicious code in the custom class field due to insufficient validation of administrator provided data. The Concrete CMS security team gave this vulnerability a CVSS v3.1 score of 3.1 with a vector of AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:L https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator . Thanks Alexey Solovyev for reporting.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | concrete5/concrete5 | ≥ 9.0.0RC1&&< 9.2.8 | 9.2.8 |
| 🐘Packagist | concrete5/concrete5 | all versions | 8.5.16 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for concrete5/concrete5. 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 concrete5/concrete5 to 9.2.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r7q4-cw9r-vhp4 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 GHSA-r7q4-cw9r-vhp4 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 GHSA-r7q4-cw9r-vhp4. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-r7q4-cw9r-vhp4 in your dependencies?
O3 detects GHSA-r7q4-cw9r-vhp4 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.