CVE-2021-47733 - CVE House
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Status published Medium CVE-2021-47733

CMSimple 5.4 Cross-Site Scripting via HTML Unicode Encoding

Vulnerability Description

CMSimple 5.4 contains a cross-site scripting vulnerability that allows attackers to bypass input filtering by using HTML to Unicode encoding. Attackers can inject malicious scripts by encoding payloads like ')-alert(1)// and execute arbitrary JavaScript when victims interact with delete buttons.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • heinjame

References

More from Cmsimple

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CVE-2021-47735
CMSimple 5.4 Authenticated Remote Code Execution via Template Editing
High 8.6
CVE-2021-47734
CMSimple 5.4 Authenticated Local File Inclusion Remote Code Execution
High 8.6

Affected Vendor

Affected Software

CMSimple
Vulnerable Versions:
<=5.4

Timeline

Official Publish: December 23rd, 2025
Last Modified: April 7th, 2026
Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Weaknesses (CWE)

CWE-79

MITRE ATT&CK TTPs

T1189 Drive-by Compromise
Initial Access
T1059.007 JavaScript
Execution
T1539 Steal Web Session Cookie
Collection
T1213 Data from Information Repositories
Collection
T1567 Exfiltration Over Web Service
Exfiltration
T1491.001 Defacement
Impact