GHSA-998c-q8hh-h8gv
MEDIUMGHSA-998c-q8hh-h8gv is a medium-severity (CVSS 4.8) Cross-site Scripting (XSS) vulnerability in concrete5/concrete5. O3 Security confirms whether GHSA-998c-q8hh-h8gv is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Concrete CMS stored XSS vulnerability in the "Top Navigator Bar" block
Blast Radius
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 versions 9.0.0 through 9.3.3 are affected by a stored XSS vulnerability in the "Top Navigator Bar" block. Since the "Top Navigator Bar" output was not sufficiently sanitized, a rogue administrator could add a malicious payload that could be executed when targeted users visited the home page. This does not affect versions below 9.0.0 since they do not have the Top Navigator Bar Block. Thanks, Chu Quoc Khanh for reporting.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | concrete5/concrete5 | ≥ 9.0.0&&< 9.3.3 | 9.3.3 |
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 9.3.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-998c-q8hh-h8gv 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-998c-q8hh-h8gv 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-998c-q8hh-h8gv. 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-998c-q8hh-h8gv in your dependencies?
O3 detects GHSA-998c-q8hh-h8gv across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.