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| 1 | +--- |
| 2 | +title: PDF Viewer Cross-site Scripting (XSS) Vulnerability (2025-6725) |
| 3 | +description: How to mitigate CVE-2025-6725, a Cross-site Scripting (XSS) vulnerability in the Telerik PDF Viewer for Blazor. |
| 4 | +type: troubleshooting |
| 5 | +page_title: PDF Viewer Cross-site Scripting (XSS) Vulnerability (2025-6725) |
| 6 | +slug: pdfviewer-kb-xss-vulnerability-cve-2025-6725 |
| 7 | +tags: telerik, blazor, pdfviewer, vulnerability, xss |
| 8 | +ticketid: 1689311 |
| 9 | +res_type: kb |
| 10 | +--- |
| 11 | + |
| 12 | +## Environment |
| 13 | + |
| 14 | +<table> |
| 15 | + <tbody> |
| 16 | + <tr> |
| 17 | + <td>Product</td> |
| 18 | + <td>PDF Viewer for Blazor</td> |
| 19 | + </tr> |
| 20 | + <tr> |
| 21 | + <td>Version</td> |
| 22 | + <td>From 3.6.0 to 9.0.0</td> |
| 23 | + </tr> |
| 24 | + </tbody> |
| 25 | +</table> |
| 26 | + |
| 27 | +## Description |
| 28 | + |
| 29 | +This is a security notification that explains how to mitigate a cross-site scripting (XSS) vulnerability [CVE-2025-6725](https://www.cve.org/CVERecord?id=CVE-2025-6725) in the Telerik PDF Viewer component for Blazor. |
| 30 | + |
| 31 | +* The weakness ID is [CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')](https://cwe.mitre.org/data/definitions/79.html). |
| 32 | +* The vulnerability CVSS score is `5.4` (medium). |
| 33 | + |
| 34 | +The XSS vulnerability can be exploited if a specially-crafted document is already loaded and the user engages with a tool that requires the DOM in the PDF Viewer to re-render. |
| 35 | + |
| 36 | +## Solution |
| 37 | + |
| 38 | +If your Blazor app uses the Telerik PDF Viewer, then [upgrading Telerik UI for Blazor](slug:upgrade-tutorial) to version **9.1.0** or later is strongly recommended. |
| 39 | + |
| 40 | +All customers with a Telerik license can: |
| 41 | + |
| 42 | +* Access the [Downloads page in their Telerik account](https://www.telerik.com/account/downloads/product-download). |
| 43 | +* Reference [NuGet packages on the Telerik NuGet server](slug:installation/nuget). |
| 44 | + |
| 45 | +## Notes |
| 46 | + |
| 47 | +* If you do not use the PDF Viewer in your application, the application is not vulnerable. |
| 48 | +* If you have any questions or concerns related to this issue, [open a new technical support ticket from the Telerik Support Center](https://www.telerik.com/account/support-center/contact-us/). Technical support is available to customers with an active license and support plan. |
| 49 | +* We would like to thank Harmen van Keimpema for responsibly disclosing this vulnerability. |
| 50 | + |
| 51 | +## See Also |
| 52 | + |
| 53 | +* [CVE-2025-6725](https://www.cve.org/CVERecord?id=CVE-2025-6725) |
| 54 | +* [PDF Viewer Overview](slug:pdfviewer-overview) |
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