CVE-2025-3566Public exploitNetwork attack vector

Unauthenticated file upload via unchecked extension

Published Apr 14, 2025 · Updated Aug 26, 2025

Unrestricted file upload in Jcool98 Echo 4.2 allows remote attackers to write arbitrary files through /discuss/uploadMdPic. The uploadMdPic handler takes the suffix after the last period in editormd-image-file, appends it to a generated name, and saves the file with transferTo without validating the extension or checking authorization. No authentication is required, and an uploaded active-content file can be retrieved from the server.

CVSS severity7.3
High
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unrestricted file upload in Jcool98 Echo 4.2 allows remote attackers to write arbitrary files through /discuss/uploadMdPic. The uploadMdPic handler takes the suffix after the last period in editormd-image-file, appends it to a generated name, and saves the file with transferTo without validating the extension or checking authorization. No authentication is required, and an uploaded active-content file can be retrieved from the server.

The record

CVE
CVE-2025-3566
Published
Apr 14, 2025
Updated
Aug 26, 2025
Vendor
Jcool98
Product
Echo
Classifications
CWE-284, CWE-434, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 26, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=4.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Jcool98 · Echoversion=4.2

Published CVSS scores

7.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
6.9VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
7.5VulDBAV:N/AC:L/Au:N/C:P/I:P/A:P

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
CWE-434Unrestricted Upload of File with Dangerous Type
T1190Exploit Public-Facing Application

Public exploit references

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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