Some exploit scripts printed “HTTP/1.1 1900 OK” as a marker upon success or referred to Magento error code 1900 (invalid order ID). It was never an official CVE designation.
This vulnerability allows attackers to upload malicious files by bypassing template file validation. It affects versions prior to Magento 1.9.3.3. Vulnerability Type: File Upload / Code Injection. Protection: Managed through the SUPEE-9767 security patch Summary of Risk & Mitigation Exploit Name Criticality Attack Vector Mitigation Unauthenticated RCE Apply SUPEE-5344 CVE-2015-1397 Authenticated RCE Update to 1.9.1.0+ CVE-2019-7139 Unauthenticated SQLi Apply PRODSECBUG-2198 Froghopper File Upload Bypass Apply SUPEE-9767 Magento RCE Exploit - GitHub magento 1900 exploit github link