CVE-2023-6391Public exploitNetwork attack vector

Site defacement via unverified settings update

Published Jan 29, 2024 · Updated May 29, 2025

Cross-site request forgery in Custom User CSS 0.2 and earlier allows remote attackers to overwrite site CSS via a forged admin request. The settings handler accepts an action=update POST containing custom_user_css_css and writes the supplied CSS without validating a CSRF token. A logged-in administrator must open an attacker-controlled page that submits the form; the demonstrated consequence is site defacement through replaced CSS.

CVSS severity8.8
High
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site request forgery in Custom User CSS 0.2 and earlier allows remote attackers to overwrite site CSS via a forged admin request. The settings handler accepts an action=update POST containing custom_user_css_css and writes the supplied CSS without validating a CSRF token. A logged-in administrator must open an attacker-controlled page that submits the form; the demonstrated consequence is site defacement through replaced CSS.

The record

CVE
CVE-2023-6391
Published
Jan 29, 2024
Updated
May 29, 2025
Vendor
Jeremiah Orem
Product
Custom User CSS
Classifications
CWE-352, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 29, 2024CVE publishedPublication date reported by the CVE source.
  2. May 29, 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=0 <=0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Jeremiah Orem · Custom User CSSversion=0 <=0.2

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/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 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-352Cross-Site Request Forgery (CSRF)
T1204.001Malicious Link

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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