CVE-2026-79670Public exploitNetwork attack vector

Stored XSS via client-declared upload types

Published Aug 25, 2026 · Updated Aug 25, 2026

Stored XSS in Ech0 before 4.4.3 allows remote authenticated users to execute JavaScript in its origin through a crafted upload. The upload handler in internal/service/file/file.go trusts the multipart Content-Type header, preserves the supplied extension, and publishes the file without authentication. Administrator access is required to upload the payload, and JavaScript runs only after a user opens its public URL, exposing same-origin sessions and data.

CVSS severity4.8
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Ech0 before 4.4.3 allows remote authenticated users to execute JavaScript in its origin through a crafted upload. The upload handler in internal/service/file/file.go trusts the multipart Content-Type header, preserves the supplied extension, and publishes the file without authentication. Administrator access is required to upload the payload, and JavaScript runs only after a user opens its public URL, exposing same-origin sessions and data.

The record

CVE
CVE-2026-79670
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
lin-snow
Product
Ech0
Classifications
CWE-434, T1059.007, T1189
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record 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=0 <4.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

lin-snow · Ech0version=0 <4.4.3

Published CVSS scores

4.8GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/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.

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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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1059.007JavaScript/JScript
T1189Drive-by Compromise

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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