CVE-2020-15099
HIGHCVE-2020-15099 is a high-severity (CVSS 8.1) Improper Input Validation vulnerability in typo3/cms-core. O3 Security confirms whether CVE-2020-15099 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Exposure of Sensitive Information to an Unauthorized Actor 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 9.5.20, and greater than or equal to 10.0.0 and less than 10.4.6, in a case where an attacker manages to generate a valid cryptographic message authentication code (HMAC-SHA1) - either by using a different existing vulnerability or in case the internal encryptionKey was exposed - it is possible to retrieve arbitrary files of a TYPO3 installation. This includes the possibility to fetch typo3conf/LocalConfiguration.php, which again contains the encryptionKey as well as credentials of the database management system being used. In case a database server is directly accessible either via internet or in a shared hosting network, this allows the ability to completely retrieve, manipulate or delete database contents. This includes creating an administration user account - which can be used to trigger remote code execution by injecting custom extensions. This has been patched in versions 9.5.20 and 10.4.6.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | typo3/cms-core | ≥ 9.0.0&&< 9.5.20 | 9.5.20 |
| 🐘Packagist | typo3/cms-core | ≥ 10.0.0&&< 10.4.6 | 10.4.6 |
| 🐘Packagist | typo3/cms | ≥ 10.0.0&&< 10.4.6 | 10.4.6 |
| 🐘Packagist | typo3/cms | ≥ 9.0.0&&< 9.5.20 | 9.5.20 |
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 9.5.20 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15099 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-2020-15099 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-2020-15099. 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-2020-15099 in your dependencies?
O3 detects CVE-2020-15099 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.