CVE-2023-4395Public exploitNetwork attack vector

Stored XSS via asset upload validation bypass

Published Aug 17, 2023 · Updated Oct 3, 2024

Stored XSS in Cockpit CMS before 2.6.4 allows remote authenticated users to execute script in another user's browser via asset uploads. The asset uploader derives MIME type from an attacker-controlled destination name instead of the uploaded temporary file and fails to isolate the URL path before checking its extension. Asset-upload permission is required; opening the stored HTML asset runs attacker-supplied script in the viewer's Cockpit origin.

CVSS severity8.1
High
EPSS probability0.57%
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 Cockpit CMS before 2.6.4 allows remote authenticated users to execute script in another user's browser via asset uploads. The asset uploader derives MIME type from an attacker-controlled destination name instead of the uploaded temporary file and fails to isolate the URL path before checking its extension. Asset-upload permission is required; opening the stored HTML asset runs attacker-supplied script in the viewer's Cockpit origin.

The record

CVE
CVE-2023-4395
Published
Aug 17, 2023
Updated
Oct 3, 2024
Vendor
Cockpit HQ
Product
Cockpit CMS
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 3, 2024Record 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 <2.6.4
  2. Affected versionversion=unspecified <2.6.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cockpit HQ · Cockpit CMSversion=0 <2.6.4; version=unspecified <2.6.4

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
8.1huntr.devCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

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-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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