CVE-2018-14773
MEDIUMSymfony HTTP Foundation web cache poisoning
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
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 | 2.7.49 |
| 🐘Packagist | symfony/http-foundation | ≥ 2.8.0&&< 2.8.44 | 2.8.44 |
| 🐘Packagist | symfony/http-foundation | ≥ 3.0.0&&< 3.3.18 | 3.3.18 |
| 🐘Packagist | symfony/http-foundation | ≥ 3.4.0&&< 3.4.14 | 3.4.14 |
| 🐘Packagist | symfony/http-foundation | ≥ 4.0.0&&< 4.0.14 | 4.0.14 |
| 🐘Packagist | symfony/http-foundation | ≥ 4.1.0&&< 4.1.3 | 4.1.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/http-foundation. 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/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.
How O3 protects you
O3 pinpoints whether CVE-2018-14773 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-2018-14773. 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-2018-14773 in your dependencies?
O3 detects CVE-2018-14773 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.