CVE-2023-4653Public exploitNetwork attack vector

Stored XSS via unsanitized Redactor HTML

Published Aug 31, 2023 · Updated Oct 1, 2024

Stored XSS in InstantCMS 2 before 2.16.1-git allows remote authenticated users to run script in another user's browser via crafted editor content. The external Imperavi Redactor editor inserted stored HTML without filtering dangerous event-handler attributes or javascript and data:text/html URLs until upstream code added sanitizeHTML processing. Exploitation requires an authenticated user who can submit editor content and another user to view it; the demonstrated impact is script execution in that viewer's browser, enabling data access or actions within that session.

CVSS severity4.8
Medium
EPSS probability0.49%
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 InstantCMS 2 before 2.16.1-git allows remote authenticated users to run script in another user's browser via crafted editor content. The external Imperavi Redactor editor inserted stored HTML without filtering dangerous event-handler attributes or javascript and data:text/html URLs until upstream code added sanitizeHTML processing. Exploitation requires an authenticated user who can submit editor content and another user to view it; the demonstrated impact is script execution in that viewer's browser, enabling data access or actions within that session.

The record

CVE
CVE-2023-4653
Published
Aug 31, 2023
Updated
Oct 1, 2024
Vendor
InstantCMS Team
Product
InstantCMS 2
Classifications
CWE-79
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 31, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 1, 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=unspecified <2.16.1-git

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

InstantCMS Team · InstantCMS 2version=unspecified <2.16.1-git

Published CVSS scores

4.8NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
5.9huntr.devCVSS:3.0/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

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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