CVE-2017-16790 is a medium-severity (CVSS 6.5) Improper Input Validation vulnerability in symfony/form. A fix is available for symfony/form — see the affected versions and patch details below.
Symfony SSRF Vulnerability via Form Component
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
symfony/form🐘symfony/form🐘symfony/form🐘symfony/form🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfonyReal-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 before 2.7.38, 2.8.31, 3.2.14, 3.3.13, 3.4-BETA5, and 4.0-BETA5. When a form is submitted by the user, the request handler classes of the Form component merge POST data and uploaded files data into one array. This big array forms the data that are then bound to the form. At this stage there is no difference anymore between submitted POST data and uploaded files. A user can send a crafted HTTP request where the value of a "FileType" is sent as normal POST data that could be interpreted as a local file path on the server-side (for example, "file:///etc/passwd"). If the application did not perform any additional checks about the value submitted to the "FileType", the contents of the given file on the server could have been exposed to the attacker.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/form | ≥ 2.7.0&&< 2.7.38 | 2.7.38composer require symfony/form:^2.7.38 |
| 🐘Packagist | symfony/form | ≥ 2.8.0&&< 2.8.31 | 2.8.31composer require symfony/form:^2.8.31 |
| 🐘Packagist | symfony/form | ≥ 3.0.0&&< 3.2.14 | 3.2.14composer require symfony/form:^3.2.14 |
| 🐘Packagist | symfony/form | ≥ 3.3.0&&< 3.3.13 | 3.3.13composer require symfony/form:^3.3.13 |
| 🐘Packagist | symfony/symfony | ≥ 2.7.0&&< 2.7.38 | 2.7.38composer require symfony/symfony:^2.7.38 |
| 🐘Packagist | symfony/symfony | ≥ 2.8.0&&< 2.8.31 | 2.8.31composer require symfony/symfony:^2.8.31 |
Affected Products
debian linuxdebiansymfonysensiolabsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/form, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/form to 2.7.38 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-16790 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.
Frequently Asked Questions
Is CVE-2017-16790 in your dependencies?
Find it across Packagist, including transitive dependencies.