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VulnerabilityPublished Updated

CVE-2026-91127: flyfish-dev file-viewer · Cross-site Scripting

Affects flyfish-dev file-viewerSource CVE Database V5

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Not known to be exploited · CVSS 8.2 High : upgrade to 2.3.1 soon.

Data as of 2 Nov 2026, 22:58 UTC

CVSS 3.1 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.3.1, 0.2.2
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2 Nov 2026.

What to do

Upgrade file-viewer and doc to 2.3.1; msdoc-viewer to 0.2.2.

Affected software

ProductAffectedFixed in
flyfish-devfile-viewerAffected
  • <2.3.1
Fixed in
  • 2.3.1
@file-viewerdocAffected
  • <2.3.1
Fixed in
  • 2.3.1
flyfish-devmsdoc-viewerAffected
  • <0.2.2
Fixed in
  • 0.2.2
npmmsdoc-viewerpkg:npm/msdoc-viewerOther threatsAffected
  • <0.2.2
Fixed in
  • 0.2.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability is fixed in @file-viewer/doc version 2.3.1 and msdoc-viewer version 0.2.2. Users should upgrade to these versions or later to remediate the issue. The fix restricts allowed URL schemes in rendered links and applies additional sanitization. No other mitigation is required if these versions are deployed.

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.

References

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