GHSA-72xp-p242-47p9
Fix: symfony/symfony@bcf487cGHSA-72xp-p242-47p9 is a CWE-185 vulnerability in symfony/routing. O3 Security confirms whether GHSA-72xp-p242-47p9 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Symfony has a UrlGenerator Route-Requirement Bypass via Unanchored Regex Alternation → Off-Site //host URL Injection
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-72xp-p242-47p9.
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.
Real-World Exposure
symfony/routing🐘symfony/routing🐘symfony/routing🐘symfony/routing🐘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
Description
Symfony routes can declare a requirements regex per path parameter, e.g. a route /{_locale}/blog with requirements: { _locale: 'en|fr|de' }. The Twig path() / url() helpers (backed by UrlGenerator) validate supplied parameter values against that regex before building the URL.
UrlGenerator constructs the validation pattern as '#^'.$req.'$#', where $req is the raw requirement string. For a requirement expressed as an alternation, e.g. _locale: 'ar|bg|...|vi|...|zh_CN' (very common), ^ and $ anchor only the first and last alternatives, so any middle alternative matches as an unanchored substring. A value like /evil.com satisfies the requirement (because it contains vi), and the generated path becomes //evil.com/...: a protocol-relative URL the browser navigates off-site.
Resolution
The UrlGenerator class now wraps the requirement in a non-capturing group so the ^ and $ anchors apply to the whole alternation.
The patch for this issue is available here for branch 5.4.
Credits
Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/routing | all versions | 5.4.52 |
| 🐘Packagist | symfony/routing | ≥ 6.0.0&&< 6.4.40 | 6.4.40 |
| 🐘Packagist | symfony/routing | ≥ 7.0.0&&< 7.4.12 | 7.4.12 |
| 🐘Packagist | symfony/routing | ≥ 8.0.0&&< 8.0.12 | 8.0.12 |
| 🐘Packagist | symfony/symfony | all versions | 5.4.52 |
| 🐘Packagist | symfony/symfony | ≥ 6.0.0&&< 6.4.40 | 6.4.40 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/routing. 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/routing to 5.4.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-72xp-p242-47p9 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 GHSA-72xp-p242-47p9 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 GHSA-72xp-p242-47p9. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-72xp-p242-47p9 in your dependencies?
O3 detects GHSA-72xp-p242-47p9 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.