CVE-2018-19789
MEDIUMCVE-2018-19789 is a medium-severity (CVSS 5.3) Unrestricted File Upload vulnerability in symfony/symfony. O3 Security confirms whether CVE-2018-19789 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Symfony Path Disclosure
Blast Radius
symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/form🐘symfony/form+4 moreReal-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
An issue was discovered in Symfony 2.7.x before 2.7.50, 2.8.x before 2.8.49, 3.x before 3.4.20, 4.0.x before 4.0.15, 4.1.x before 4.1.9, and 4.2.x before 4.2.1. When using the scalar type hint string in a setter method (e.g. setName(string $name)) of a class that's the data_class of a form, and when a file upload is submitted to the corresponding field instead of a normal text input, then UploadedFile::__toString() is called which will then return and disclose the path of the uploaded file. If combined with a local file inclusion issue in certain circumstances this could escalate it to a Remote Code Execution.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/symfony | ≥ 2.7.0&&< 2.7.50 | 2.7.50 |
| 🐘Packagist | symfony/symfony | ≥ 2.8.0&&< 2.8.49 | 2.8.49 |
| 🐘Packagist | symfony/symfony | ≥ 3.0.0&&< 3.4.20 | 3.4.20 |
| 🐘Packagist | symfony/symfony | ≥ 4.0.0&&< 4.0.15 | 4.0.15 |
| 🐘Packagist | symfony/symfony | ≥ 4.1.0&&< 4.1.9 | 4.1.9 |
| 🐘Packagist | symfony/symfony | ≥ 4.2.0&&< 4.2.1 | 4.2.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/symfony. 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 symfony/symfony to 2.7.50 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-19789 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-2018-19789 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-2018-19789. 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-2018-19789 in your dependencies?
O3 detects CVE-2018-19789 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.