CVE-2026-91127Network attack vector

DOM XSS via unsafe legacy DOC hyperlinks

Published Sep 18, 2026 · Updated Sep 18, 2026

DOM XSS in Flyfish File Viewer before 2.3.1 allows remote attackers to execute script through a crafted legacy DOC hyperlink. The legacy DOC renderer HTML-escapes document-controlled hyperlink targets but emits them without restricting schemes such as javascript:, vbscript:, or data:. A user must open the crafted document and click its link, after which script runs in the embedding application's origin and can read origin-accessible data or alter page content.

CVSS severity8.2
High
EPSS probability0.40%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DOM XSS in Flyfish File Viewer before 2.3.1 allows remote attackers to execute script through a crafted legacy DOC hyperlink. The legacy DOC renderer HTML-escapes document-controlled hyperlink targets but emits them without restricting schemes such as javascript:, vbscript:, or data:. A user must open the crafted document and click its link, after which script runs in the embedding application's origin and can read origin-accessible data or alter page content.

The record

CVE
CVE-2026-91127
Published
Sep 18, 2026
Updated
Sep 18, 2026
Vendor
Flyfish Dev
Product
@file-viewer/doc
Classifications
CWE-83, CWE-79, T1203, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Flyfish Dev · @file-viewer/docversion=< 0.2.2
Flyfish Dev · Flyfish File Viewerversion=< 2.3.1
Flyfish · @file-viewer/docversion=< 2.3.1

Published CVSS scores

8.2GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-83Improper Neutralization of Script in Attributes in a Web Page
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution
T1204.001Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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