CVE-2026-91127 Details
Description
File Viewer is a browser-native viewer for Office, PDF, CAD, archive, and other files in private and internal web applications. Prior to @file-viewer/doc 2.3.1 and msdoc-viewer 0.2.2, the legacy DOC renderer emitted document-controlled hyperlink targets into generated HTML after character escaping but without restricting URL schemes. A crafted legacy DOC file could place javascript:, vbscript:, data:, or another unsafe scheme in a rendered link, and script could execute in the embedding application's origin when a user clicked the link. The fix blocks external document links by default, allows only HTTP(S), mail, telephone, safe relative URLs, and internal bookmarks when external links are explicitly enabled, and applies mount-boundary sanitization as defense in depth. This issue is fixed in @file-viewer/doc 2.3.1 and msdoc-viewer 0.2.2.
A DOM-based cross-site scripting vulnerability has been identified in the legacy DOC renderer of File Viewer versions prior to 2.3.1 and msdoc-viewer versions prior to 0.2.2. The issue arises because the DOC renderer processed hyperlink targets from documents after escaping them for HTML, but without restricting the URL schemes. This oversight allowed a maliciously crafted DOC file to introduce links with unsafe schemes, such as javascript:, vbscript:, or data:, which could execute scripts in the context of the application's origin when clicked by a user.
Users can upgrade to File Viewer version 2.3.1 or msdoc-viewer version 0.2.2 to address this vulnerability. Instructions for downloading these versions are available on the GitHub Releases page for the File Viewer project.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 18, 2026CISA-ADP
Assessed Sep 22, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/flyfish-dev/file-viewer/commit/ef045680f8d9830a3eee9612f7df46a734361b07 | [email protected] | Source CodeVendor |
| https://github.com/flyfish-dev/file-viewer/releases/tag/v2.3.1 | [email protected] | Release NotesVendor |
| https://github.com/flyfish-dev/file-viewer/security/advisories/GHSA-3753-m2x2-q623 | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
| CWE-83 | Improper Neutralization of Script in Attributes in a Web Page | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| flyfish-dev File Viewer | <= 2.3.0 (semver) |
CPE
Remediation
| |
| flyfish-dev msdoc-viewer | <= 0.2.1 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 22, 2026 | CVE Modified | CISA-ADP |
| Sep 18, 2026 | New CVE Received | [email protected] |