CVE-2025-6725 – This CVE describes a Cross-Site Scripting (XSS)... (How to Fix)

Q: What is the severity of CVE-2025-6725?

CVE-2025-6725 has a CVSS score of 5.4 (MEDIUM). This CVE describes a Cross-Site Scripting (XSS) vulnerability in Telerik's PdfViewer component across multiple UI frameworks. Attackers can execute arbitrary JavaScript in victims' browsers by tricking them into loading a malicious PDF document and then interacting with certain viewer tools. This affects web applications using vulnerable versions of Telerik UI components.

📋 TL;DR

This CVE describes a Cross-Site Scripting (XSS) vulnerability in Telerik's PdfViewer component across multiple UI frameworks. Attackers can execute arbitrary JavaScript in victims' browsers by tricking them into loading a malicious PDF document and then interacting with certain viewer tools. This affects web applications using vulnerable versions of Telerik UI components.

💻 Affected Systems

Products:

Telerik UI for ASP.NET Core
Telerik UI for ASP.NET MVC
Telerik UI for Blazor
Kendo UI for Angular
Kendo UI for jQuery

Versions: Specific vulnerable versions not specified in references; check vendor advisories for exact ranges

Operating Systems: All

Default Config Vulnerable: ⚠️ Yes

Notes: Vulnerability requires user interaction with PDF viewer tools after loading a malicious document; affects web applications using these components.

⚠️ Manual Verification Required

This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.

Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).

🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.

Recommended Actions:

Review the CVE details at NVD
Check vendor security advisories for your specific version
Test if the vulnerability is exploitable in your environment
Consider updating to the latest version as a precaution

⚠️ Risk & Real-World Impact

🔴

Worst Case

Attackers could steal session cookies, perform actions as the authenticated user, redirect to malicious sites, or install malware through drive-by downloads.

🟠

Likely Case

Session hijacking, credential theft, or defacement of the application interface through injected content.

🟢

If Mitigated

Limited impact with proper Content Security Policy (CSP) headers and input sanitization, though some functionality may be disrupted.

🌐 Internet-Facing: MEDIUM

🏢 Internal Only: LOW

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires user to load a malicious PDF and interact with viewer tools; no authentication needed but requires social engineering or compromised document sources.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check specific product documentation for patched versions

Vendor Advisory: https://www.telerik.com/aspnet-core-ui/documentation/knowledge-base/kb-security-pdfviewer-xss-cve-2025-6725

Restart Required: No

Instructions:

1. Identify affected Telerik/Kendo UI components in your application. 2. Update to the latest patched version for your specific framework (ASP.NET Core, MVC, Blazor, Angular, or jQuery). 3. Rebuild and redeploy the application. 4. Test PDF viewer functionality.

🔧 Temporary Workarounds

Implement Content Security Policy

all

Add strict CSP headers to prevent execution of inline scripts and restrict script sources.

Content-Security-Policy: default-src 'self'; script-src 'self' https://trusted.cdn.com; object-src 'none';

Disable PDF Viewer Tools

all

Temporarily disable interactive tools in the PDF viewer that trigger DOM re-rendering.

Configure PdfViewer component to disable annotation, selection, or other interactive tools via component settings.

🧯 If You Can't Patch

Implement strict Content Security Policy headers to block inline scripts and untrusted sources.
Sanitize all PDF content before rendering using server-side validation libraries.

🔍 How to Verify

Check if Vulnerable:

Check your application's package.json, .csproj, or dependency files for Telerik/Kendo UI components and compare versions against vendor advisories.

Check Version:

For .NET: check packages.config or .csproj for Telerik/Kendo references. For JavaScript: check package.json for @progress/kendo-angular-pdfviewer or similar.

Verify Fix Applied:

After updating, verify the component version matches patched releases and test PDF loading with sample malicious content (in safe environment).

📡 Detection & Monitoring

Log Indicators:

Unusual PDF file uploads or requests with suspicious parameters
JavaScript errors in browser console logs related to PDF rendering

Network Indicators:

Requests to external domains from PDF viewer context
Unusual Content-Type headers in PDF responses

SIEM Query:

source="web_server" AND (uri="*.pdf" OR user_agent="*PdfViewer*") AND status=200

📊 Metadata

CVE ID: CVE-2025-6725

CVSS v3 Score: 5.4 (MEDIUM)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CWE: CWE-79

EPSS Score: 0.04% exploit probability (13.2th percentile)

Published: July 2, 2025

Last Updated: July 3, 2025

🔗 References

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