Administrator-context script execution via unencoded Message output
Published Mar 16, 2026 · Updated Mar 16, 2026
Cross-site scripting in CMS Made Simple 2.2.21 and earlier allows remote authenticated users to execute script via the Message parameter. In admin/listusers.php, User Management applies blacklist-style filtering to Message but concatenates the result into HTML without contextual output encoding. Administrative access and victim interaction are required; successful exploitation runs attacker-controlled JavaScript in the administrative origin.
Summary
What happened
Cross-site scripting in CMS Made Simple 2.2.21 and earlier allows remote authenticated users to execute script via the Message parameter. In admin/listusers.php, User Management applies blacklist-style filtering to Message but concatenates the result into HTML without contextual output encoding. Administrative access and victim interaction are required; successful exploitation runs attacker-controlled JavaScript in the administrative origin.
The record
- CVE
- CVE-2026-4225
- Published
- Mar 16, 2026
- Updated
- Mar 16, 2026
- Vendor
- CMS Made Simple Foundation
- Product
- CMS Made Simple
- Classifications
- CWE-94, CWE-79, T1203
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Mar 16, 2026CVE publishedPublication date reported by the CVE source.
- Mar 16, 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.
- Affected versionversion=2.2.0
- Affected versionversion=2.2.1
- Affected versionversion=2.2.10
- Affected versionversion=2.2.11
- Affected versionversion=2.2.12
- Affected versionversion=2.2.13
- Affected versionversion=2.2.14
- Affected versionversion=2.2.15
- Affected versionversion=2.2.16
- Affected versionversion=2.2.17
- Affected versionversion=2.2.18
- Affected versionversion=2.2.19
- Affected versionversion=2.2.2
- Affected versionversion=2.2.20
- Affected versionversion=2.2.21
- Affected versionversion=2.2.3
- Affected versionversion=2.2.4
- Affected versionversion=2.2.5
- Affected versionversion=2.2.6
- Affected versionversion=2.2.7
- Affected versionversion=2.2.8
- Affected versionversion=2.2.9
What conditions does exploitation require?
What is affected?
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.
Weakness, pattern, technique
Public exploit references
- CMS Made Simple 2.2.21 XSS reproductionproof of concept · unverified
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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