GHSA-4j77-gg36-9864
MEDIUMGHSA-4j77-gg36-9864 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in typo3/cms-core. O3 Security confirms whether GHSA-4j77-gg36-9864 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Cross-Site Scripting in TYPO3 CMS Link Handling
Real-World Exposure
typo3/cms-core🐘typo3/cms-core🐘typo3/cms🐘typo3/cmsReal-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
It has been discovered that link tags generated by typolink functionality are vulnerable to cross-site scripting - properties being assigned as HTML attributes have not been parsed correctly.
Update to TYPO3 versions 9.5.17 or 10.4.2 that fix the problem described.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | typo3/cms-core | ≥ 10.0.0&&< 10.4.2 | 10.4.2 |
| 🐘Packagist | typo3/cms-core | ≥ 9.0.0&&< 9.5.17 | 9.5.17 |
| 🐘Packagist | typo3/cms | ≥ 10.0.0&&< 10.4.2 | 10.4.2 |
| 🐘Packagist | typo3/cms | ≥ 9.0.0&&< 9.5.17 | 9.5.17 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for typo3/cms-core. 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 typo3/cms-core to 10.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4j77-gg36-9864 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-4j77-gg36-9864 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-4j77-gg36-9864. 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-4j77-gg36-9864 in your dependencies?
O3 detects GHSA-4j77-gg36-9864 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.