CVE-2026-48796 is a medium-severity (CVSS 5.3) Path Traversal vulnerability in CefSharp.Common. O3 Security confirms whether CVE-2026-48796 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
CefSharp: `FolderSchemeHandlerFactory` path boundary check can expose files outside the configured root folder
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 CVE-2026-48796.
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-2026-48796 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 369,023 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
CefSharp.CommonReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
CefSharp provides .NET bindings for the Chromium Embedded Framework for Windows Forms and Windows Presentation Foundation applications. Prior to version 148.0.90, CefSharp/SchemeHandler/FolderSchemeHandlerFactory.cs used filePath.StartsWith(rootFolder, StringComparison.OrdinalIgnoreCase) to decide whether a decoded and canonicalized request path remained inside rootFolder. That raw prefix test did not enforce a directory boundary, so a request such as ..%2fwww2/secret.txt could escape a configured www directory into a sibling www2 directory whose path shared the same string prefix. Applications that register FolderSchemeHandlerFactory for a custom scheme or an HTTP or HTTPS scheme can therefore serve local files outside the intended root when an attacker can cause the embedded browser to request the crafted URL. The issue affects both Unix-style paths such as /tmp/app/www2 and Windows paths such as C:\app\www2, and the fix appends a directory separator to the normalized root before comparison while rejecting null bytes and alternate data stream syntax. This issue is fixed in version 148.0.90.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | CefSharp.Common | all versions | 148.0.90 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for CefSharp.Common. 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 CefSharp.Common to 148.0.90 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48796 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-2026-48796 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-2026-48796. 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-2026-48796 in your dependencies?
O3 detects CVE-2026-48796 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.