CVE-2026-48784
Symfony: UrlGenerator Dot-Segment Encoding Skips Every Other Chained `../` or `./` → Generated URL Collapses Off-Route Under RFC 3986 Normalization
Blast Radius
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
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.53, 6.4.41, 7.4.13, and 8.0.13, UrlGenerator::doGenerate() used strtr() dot-segment encoding that skipped every other chained ../ or ./ segment, allowing attacker-controlled route parameters to generate URLs that collapse to a different path under RFC 3986 normalization. This issue is fixed in versions 5.4.53, 6.4.41, 7.4.13, and 8.0.13.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/routing | all versions | 5.4.53 |
| 🐘Packagist | symfony/routing | ≥ 6.0.0&&< 6.4.41 | 6.4.41 |
| 🐘Packagist | symfony/routing | ≥ 7.0.0&&< 7.4.13 | 7.4.13 |
| 🐘Packagist | symfony/routing | ≥ 8.0.0&&< 8.0.13 | 8.0.13 |
| 🐘Packagist | symfony/symfony | all versions | 5.4.53 |
| 🐘Packagist | symfony/symfony | ≥ 6.0.0&&< 6.4.41 | 6.4.41 |
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 5.4.53 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48784 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-2026-48784 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-2026-48784. 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-2026-48784 in your dependencies?
O3 detects CVE-2026-48784 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.