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Vulnerability record · CVE-2021-47733 · published 23 December 2025

CVE-2021-47733: Cmsimple cross-site scripting vulnerability

Cmsimple · Cmsimple

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.

5.1 CVSS 4.0 Medium EPSS 0.26% · top 83.6% CWE-79 · Cross-site scripting
5.1CVSS 4.0 base score
0.26%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 1 tagged exploit
17 Jun 2026Last modified by NVD

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://www.cmsimple.org/en/ Product
https://www.exploit-db.com/exploits/50612 Exploit
https://www.vulncheck.com/advisories/cmsimple-cross-site-scripting-via-html-unicode-encoding Third Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-43741Cmsimple path traversal vulnerabilityCMSimple 5.4 is vulnerable to Directory Traversal. The vulnerability exists when a user changes the file name to malicious file on config.php leading…EPSS 4.7%9.1CVE-2024-57548Cmsimple incorrect default permissions vulnerabilityCMSimple 5.16 allows the user to edit log.php file via print page.EPSS 0.47%8.6CVE-2021-47734Cmsimple php remote file inclusion vulnerabilityCMSimple 5.4 contains an authenticated local file inclusion vulnerability that allows remote attackers to manipulate PHP session files and execute ar…EPSS 0.78%8.6CVE-2021-47735Cmsimple code injection vulnerabilityCMSimple 5.4 contains an authenticated remote code execution vulnerability that allows logged-in attackers to inject malicious PHP code into template…EPSS 0.88%8.6CVE-2024-58280Cmsimple vulnerabilityCMSimple 5.15 contains a remote command execution vulnerability that allows authenticated attackers to modify file extensions and upload malicious PH…EPSS 0.94%7.5CVE-2024-57547Cmsimple incorrect permission assignment vulnerabilityInsecure Permissions vulnerability in CMSimple v.5.16 allows a remote attacker to obtain sensitive information via a crafted script to the Functional…EPSS 0.57%7.5CVE-2024-57549Cmsimple path traversal vulnerabilityCMSimple 5.16 allows the user to read cms source code through manipulation of the file name in the file parameter of a GET request.EPSS 0.66%7.5CVE-2024-57546Cmsimple vulnerabilityAn issue in CMSimple v.5.16 allows a remote attacker to obtain sensitive information via a crafted script to the validate link function.EPSS 0.58%

Source: NIST National Vulnerability Database (record CVE-2021-47733), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.