Vulnerability · Published Sep 18, 2026 · Assigned by GitHub_M
CVE-2026-91127File Viewer: DOM XSS via unsafe hyperlink schemes in the legacy DOC renderer
High 8.2
In plain English
A high-severity cross-site scripting in doc from @file-viewer. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | @file-viewer/doc | 2.3.1 | GHSA-3753-m2x2-q623 |
| npm | msdoc-viewer | 0.2.2 | GHSA-3753-m2x2-q623 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| flyfish-dev | file-viewer | < 2.3.1 |
| @file-viewer | doc | < 2.3.1 |
| flyfish-dev | msdoc-viewer | < 0.2.2 |
Weakness: CWE-79, CWE-83 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N