CVE-2023-53921

CriticalPublic PoC

Published: 17 December 2025

Published

17 December 2025

Modified

31 December 2025

KEV Added

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Patch

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CVSS Score 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Score 0.0039 59.8th percentile

Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2023-53921 is a critical-severity Unrestricted Upload of File with Dangerous Type (CWE-434) vulnerability in Sitemagic Sitemagic Cms. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 40.2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 CM-6 (Configuration Settings) and SI-10 (Information Input Validation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190). What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

Directly remediates the specific unrestricted file upload flaw in SitemagicCMS by applying vendor-provided patches to prevent malicious .phar uploads.

SI-10 Information Input Validation good match

prevent

Validates file uploads to block dangerous types like .phar containing PHP code execution payloads, addressing the core CWE-434 vulnerability.

CM-6 Configuration Settings good match

prevent

Enforces secure configuration settings on the web server to disable script execution in the files/images directory, preventing RCE even if malicious files are uploaded.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

Why these techniques?

The vulnerability is an unauthenticated remote code execution via unrestricted upload of dangerous files (.phar with command execution payloads) in a public-facing web application, directly enabling T1190: Exploit Public-Facing Application.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

SitemagicCMS 4.4.3 contains a remote code execution vulnerability that allows attackers to upload malicious PHP files to the files/images directory. Attackers can upload a .phar file with system command execution payload to compromise the web application and execute arbitrary system…

commands.

Deeper analysisAI

SitemagicCMS version 4.4.3 is affected by CVE-2023-53921, a remote code execution vulnerability stemming from CWE-434 (Unrestricted Upload of File with Dangerous Type). The flaw enables attackers to upload malicious PHP files, specifically .phar files containing system command execution payloads, to the files/images directory of the web application. This critical issue carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), highlighting its severity due to high confidentiality, integrity, and availability impacts.

Unauthenticated remote attackers can exploit this vulnerability over the network with low complexity and no user interaction required. By uploading a crafted .phar file to the vulnerable directory, attackers gain the ability to compromise the web application and execute arbitrary system commands on the underlying server, potentially leading to full server takeover.

Advisories from Vulncheck document the unrestricted file upload leading to remote code execution, while a public proof-of-concept exploit is available on Exploit-DB (ID 51464). The vendor's download page at sitemagic.org provides access to software updates, which security practitioners should review for patches addressing this issue.