CVE-2026-54910 is a high-severity (CVSS 7.7) Path Traversal vulnerability in github.com/gtsteffaniak/filebrowser/backend. O3 Security confirms whether CVE-2026-54910 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
FileBrowser Quantum's path traversal issue in subtitle handler allows any authenticated user to read arbitrary files
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54910.
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.
How urgent is this, really
CVE-2026-54910 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 371,256 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/gtsteffaniak/filebrowser/backendReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
FileBrowser Quantum is a free, self-hosted, web-based file manager. Prior to version 1.4.3-beta, the subtitlesHandler endpoint (GET /api/media/subtitles) accepts two user-controlled query parameters: path and name, both of which are used in filesystem operations without sanitization, creating two independent path traversal vectors. The primary vector is the path parameter: it is passed directly to idx.GetRealPath() without calling SanitizeUserPath(), allowing an attacker to escape the storage root and set parentDir to any directory on the host. No existing anchor file is required. The secondary vector is the name parameter: it is joined with parentDir via filepath.Join(parentDir, name) without stripping directory components, allowing traversal relative to any resolved parentDir. Any authenticated user (regardless of role or permissions) can exploit either vector to read any text file readable by the server process, including /etc/passwd, SSH keys, database credentials, and JWT signing keys. Version 1.4.3-beta patches the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/gtsteffaniak/filebrowser/backend | all versions | 0.0.0-20260608182036-f3f4bbe80cb5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gtsteffaniak/filebrowser/backend. 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 github.com/gtsteffaniak/filebrowser/backend to 0.0.0-20260608182036-f3f4bbe80cb5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54910 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-2026-54910 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-2026-54910. 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-2026-54910 in your dependencies?
O3 detects CVE-2026-54910 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.