CVE-2026-91127
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.
What this means for your business
- An attacker can use it remotely, over a network, without a login, but only after tricking someone into an action such as opening a file or a link.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
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Scoring
- CVSS
- 8.2 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N- Weakness
- CWE-79
- Assigned by
- security-advisories@github.com
Dates
- Published
- 2026-09-18
- Last modified
- 2026-09-18
- Sources
- NVD