CVE-2026-54087 is a high-severity (CVSS 7.6) remote code execution vulnerability in easycorp/easyadmin-bundle. O3 Security confirms whether CVE-2026-54087 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
EasyAdmin: Stored Cross-Site Scripting (XSS) via uploaded files served inline in FileField and ImageField
Real-World Exposure
easycorp/easyadmin-bundleReal-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
EasyAdmin's FileField and ImageField accept browser-executable file types by default (FileField applies no MIME/extension restrictions; ImageField's default Image constraint accepts SVG). When the upload directory is configured inside the public web root — as shown in the documentation — EasyAdmin links to the stored file inline (no download attribute or Content-Disposition: attachment).
An attacker with access to a form using these fields can upload an .html (FileField) or .svg (ImageField) file containing JavaScript. When another user opens it from the backend, it is served from the same origin and the script executes in the context of their authenticated admin session, enabling session/CSRF-token theft or privilege escalation.
Exploitation requires the developer to store uploads in the public directory and a privilege gap between the uploading user and the viewing administrator. This is stored XSS only — it does not allow remote code execution, because uploaded filenames are derived from Symfony's guessExtension(), which never produces .php/.phtml.
Credit
We would like to thank Emre Dogan for reporting the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | easycorp/easyadmin-bundle | ≥ 5.0.0&&< 5.0.13 | 5.0.13 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for easycorp/easyadmin-bundle. 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 easycorp/easyadmin-bundle to 5.0.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54087 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-2026-54087 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-2026-54087. 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-2026-54087 in your dependencies?
O3 detects CVE-2026-54087 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.