CVE-2023-4189Public exploitNetwork attack vector

Browser script execution via unescaped form attributes

Published Aug 5, 2023 · Updated Oct 9, 2024

Reflected XSS in InstantCMS and InstantCMS 2 before 2.16.1-git allows remote authenticated users to run script in another user's browser. Administrative form, filter, and menu templates place attacker-controlled URLs or titles into HTML attributes and page output without html() encoding. Administrator-level access and user interaction are required; execution remains in the victim's browser context, where page data or actions can be exposed or altered.

CVSS severity4.8
Medium
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in InstantCMS and InstantCMS 2 before 2.16.1-git allows remote authenticated users to run script in another user's browser. Administrative form, filter, and menu templates place attacker-controlled URLs or titles into HTML attributes and page output without html() encoding. Administrator-level access and user interaction are required; execution remains in the victim's browser context, where page data or actions can be exposed or altered.

The record

CVE
CVE-2023-4189
Published
Aug 5, 2023
Updated
Oct 9, 2024
Vendor
InstantCMS Team
Product
InstantCMS
Classifications
CWE-79, T1203
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Aug 5, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 9, 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 <2.16.1-git

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

InstantCMS Team · InstantCMSversion=0 <2.16.1-git
InstantCMS Team · InstantCMS 2version=unspecified <2.16.1-git

Published CVSS scores

4.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
4.8huntr.devCVSS:3.0/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-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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