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CVE-2026-48796 medium CVSS 5.3

Path Traversal in CefSharp.Common (CVE-2026-48796)

Summary

Path traversal in CefSharp.Common (CVE-2026-48796). Confidential information can be exposed externally. Exploitable via FolderSchemeHandlerFactory. Mitigation: upgrade to 148.0.90 or later.

Original description

The description as published by the source.

Summary

FolderSchemeHandlerFactory was intended to restrict served files to a configured rootFolder, but its path validation used a raw string prefix check. A request could escape to a sibling directory whose full path starts with the root folder path, allowing files outside the configured root to be served.

Details

In affected versions, FolderSchemeHandlerFactory canonicalized rootFolder, decoded the request path, combined it with the root, and then allowed the file when:

filePath.StartsWith(rootFolder, StringComparison.OrdinalIgnoreCase)

This does not enforce a directory boundary. For example, /tmp/app/www2/secret.txt starts with /tmp/app/www, but www2 is a sibling of www, not a child. The same issue applies on Windows, for example C:\app\www2\secret.txt starts with C:\app\www.

The affected code was reviewed at commit b5fef3bb4bc58798c95170078c41de92cfe9066e, assembly version 147.0.100.

PoC

Set rootFolder to a directory named www and create a sibling directory named www2:

/www/index.html
/www2/secret.txt

Register FolderSchemeHandlerFactory for /www, then request:

https://folderschemehandlerfactory.test/..%2fwww2/secret.txt

The request path is URL-decoded to ../www2/secret.txt, combined with /www, and canonicalized to:

/www2/secret.txt

Because /www2/secret.txt starts with /www as a string prefix, the affected check passes and secret.txt is served from outsi…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-48796 has been found in CefSharp.Common.
Attackers can target a specific entry point like FolderSchemeHandlerFactory over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 5.3/10.
What to do: upgrade CefSharp.Common to 148.0.90 or later.
If unsure, ask your IT team or search "CefSharp.Common CVE-2026-48796" on the vendor's site.

CVE-2026-48796 (CefSharp.Common) — CWE-22 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: FolderSchemeHandlerFactory / rootFolder / www2 / www
Patched: 148.0.90 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Path traversal (CWE-22) exists in CefSharp.Common. Attackers reach the vulnerable code path via FolderSchemeHandlerFactory without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of CefSharp.Common. Attack surface: FolderSchemeHandlerFactory / rootFolder / www2 / www.

🔥 Severity

Severity: Medium (CVSS 5.3/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 148.0.90.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'CefSharp.Common' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'CefSharp.Common' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で CefSharp.Common を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade CefSharp.Common to 148.0.90

    ステージング環境で 148.0.90 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

nuget CefSharp.Common
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"148.0.90"}]}]

References

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