CVE-2026-44259Public exploitNetwork attack vector

Stored XSS via executable preview MIME types

Published May 12, 2026 · Updated May 12, 2026

Stored XSS in EFW before 4.08.010 allows remote authenticated users to execute JavaScript in another user's browser through file preview. previewServlet maps .html, .htm, and .svg extensions to executable MIME types and streams file content inline without sanitization or protective response headers. The attacker must first write a crafted file to elFinder storage and entice another user to preview it, granting same-origin access to perform authenticated actions as that victim.

CVSS severity4.6
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored XSS in EFW before 4.08.010 allows remote authenticated users to execute JavaScript in another user's browser through file preview. previewServlet maps .html, .htm, and .svg extensions to executable MIME types and streams file content inline without sanitization or protective response headers. The attacker must first write a crafted file to elFinder storage and entice another user to preview it, granting same-origin access to perform authenticated actions as that victim.

The record

CVE
CVE-2026-44259
Published
May 12, 2026
Updated
May 12, 2026
Vendor
ESCCO Japan Co., Ltd.
Product
EFW
Classifications
CWE-80, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. May 12, 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=< 4.08.010

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

ESCCO Japan Co., Ltd. · EFWversion=< 4.08.010

Published CVSS scores

4.6GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/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.

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

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
T1059.007JavaScript/JScript

Public exploit references

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo