CVE-2018-14773 is a medium-severity (CVSS 6.5) vulnerability in symfony/http-foundation. EPSS puts its 30-day exploitation probability at 57.6% (99th percentile). A fix is available for symfony/http-foundation — see the affected versions and patch details below.
Symfony HTTP Foundation web cache poisoning
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/http-foundation🐘symfony/http-foundation🐘symfony/http-foundation🐘symfony/http-foundation🐘symfony/http-foundation🐘symfony/http-foundation🐘symfony/symfony🐘symfony/symfony+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 Http Foundation in Symfony 2.7.0 through 2.7.48, 2.8.0 through 2.8.43, 3.3.0 through 3.3.17, 3.4.0 through 3.4.13, 4.0.0 through 4.0.13, and 4.1.0 through 4.1.2. It arises from support for a (legacy) IIS header that lets users override the path in the request URL via the X-Original-URL or X-Rewrite-URL HTTP request header. These headers are designed for IIS support, but it's not verified that the server is in fact running IIS, which means anybody who can send these requests to an application can trigger this. This affects \Symfony\Component\HttpFoundation\Request::prepareRequestUri() where X-Original-URL and X_REWRITE_URL are both used. The fix drops support for these methods so that they cannot be used as attack vectors such as web cache poisoning.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/http-foundation | ≥ 2.7.0&&< 2.7.49 | 2.7.49composer require symfony/http-foundation:^2.7.49 |
| 🐘Packagist | symfony/http-foundation | ≥ 2.8.0&&< 2.8.44 | 2.8.44composer require symfony/http-foundation:^2.8.44 |
| 🐘Packagist | symfony/http-foundation | ≥ 3.0.0&&< 3.3.18 | 3.3.18composer require symfony/http-foundation:^3.3.18 |
| 🐘Packagist | symfony/http-foundation | ≥ 3.4.0&&< 3.4.14 | 3.4.14composer require symfony/http-foundation:^3.4.14 |
| 🐘Packagist | symfony/http-foundation | ≥ 4.0.0&&< 4.0.14 | 4.0.14composer require symfony/http-foundation:^4.0.14 |
| 🐘Packagist | symfony/http-foundation | ≥ 4.1.0&&< 4.1.3 | 4.1.3composer require symfony/http-foundation:^4.1.3 |
Affected Products
debian linuxdebiandrupaldrupalsymfonysensiolabsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/http-foundation, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/http-foundation to 2.7.49 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-14773 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-2018-14773 in your dependencies?
Find it across Packagist, including transitive dependencies.