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File Viewer EUVDEUVD-2026-83206

| CVE-2026-91127 HIGH
Cross-site Scripting (XSS) (CWE-79)
2026-09-18 GitHub_M GHSA-3753-m2x2-q623
8.2
CVSS 3.1 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
8.2 HIGH
AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
vuln.today AI
8.2 HIGH

Unauthenticated remote (PR:N/AV:N), but victim must click the malicious link (UI:R); script escapes render context into host origin (S:C) enabling data theft (C:H) and limited tampering (I:L).

3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:L/SI:L/SA:N

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
None

Lifecycle Timeline

6
POC Analysis Generated
Sep 18, 2026 - 19:22 vuln.today
Metadata Corrected
Sep 18, 2026 - 18:40 vuln.today
tag: npm added
Metadata Corrected
Sep 18, 2026 - 18:40 vuln.today
tag: Microsoft removed
Patch available
Sep 18, 2026 - 18:03 EUVD
Analysis Generated
Sep 18, 2026 - 17:55 vuln.today
CVE Published
Sep 18, 2026 - 17:18 cve.org
HIGH 8.2

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 12 npm packages depend on @file-viewer/doc (2 direct, 10 indirect)

Ecosystem-wide dependent count for version 2.3.1.

DescriptionCVE.org

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.

AnalysisAI

The legacy DOC renderer in File Viewer emits document-controlled hyperlink targets into generated HTML after character escaping but without restricting URL schemes, so a crafted legacy .doc file can render a live javascript:, vbscript:, or data: link and execute script in the embedding application's origin when a user clicks it. Applications are affected if they use @file-viewer/doc up to and including 2.3.0 or the msdoc-viewer compatibility package up to and including 0.2.1 to render untrusted .doc files; exploitation is conditionally gated, requiring a victim to open the preview and click the malicious link (CVSS 8.2, UI:R, scope changed). …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
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Delivery
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Exploit
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Execution
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Impact
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Vulnerability AssessmentAI

Exploitation Requires that the embedding application uses @file-viewer/doc ≤2.3.0 or msdoc-viewer ≤0.2.1 to render UNTRUSTED legacy .doc files, and that a user opens the preview and CLICKS an attacker-controlled hyperlink (UI:R). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a genuine but conditionally-gated client-side XSS (CWE-79) rather than a mass-exploitable network flaw. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Upgrade to the vendor-released fixed versions: @file-viewer/doc 2.3.1, msdoc-viewer 0.2.2, and @file-viewer/renderer-word 2.3.2, or the 2.3.4 patch line for the Office/Full/copy-assets bundles (for example pnpm add @file-viewer/vue3-full@2.3.4); the fix commit is https://github.com/flyfish-dev/file-viewer/commit/ef045680f8d9830a3eee9612f7df46a734361b07 and details are in the GHSA-3753-m2x2-q623 advisory. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, inventory all applications and services using @file-viewer/doc up to and including 2.3.0 or msdoc-viewer up to and including 0.2.1 to render untrusted .doc files, disable or tightly restrict legacy .doc previews where business use is not essential, and block javascript:, vbscript:, and data: hyperlink schemes in rendered documents via sanitization or a strict Content Security Policy. …

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EUVD-2026-83206 vulnerability details – vuln.today

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