CVE-2020-11066
CRITICALCVE-2020-11066 is a critical-severity (CVSS 10) remote code execution vulnerability in typo3/cms-core. O3 Security confirms whether CVE-2020-11066 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Class destructors causing side-effects when being unserialized in TYPO3 CMS
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
In TYPO3 CMS greater than or equal to 9.0.0 and less than 9.5.17 and greater than or equal to 10.0.0 and less than 10.4.2, calling unserialize() on malicious user-submitted content can lead to modification of dynamically-determined object attributes and result in triggering deletion of an arbitrary directory in the file system, if it is writable for the web server. It can also trigger message submission via email using the identity of the web site (mail relay). Another insecure deserialization vulnerability is required to actually exploit mentioned aspects. This has been fixed in 9.5.17 and 10.4.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | typo3/cms-core | ≥ 9.0.0&&< 9.5.17 | 9.5.17 |
| 🐘Packagist | typo3/cms-core | ≥ 10.0.0&&< 10.4.2 | 10.4.2 |
| 🐘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 9.5.17 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-11066 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-2020-11066 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-2020-11066. 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-2020-11066 in your dependencies?
O3 detects CVE-2020-11066 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.