CISA Urges Immediate Patching of Critical Sitecore Vulnerability Under Active Attack
September 5, 2025
Vulnerability / Threat Intelligence
Federal Civilian Executive Branch (FCEB) agencies are directed to update their Sitecore systems by September 25, 2025, due to a critical security vulnerability, identified as CVE-2025-53690, that is currently being exploited. The vulnerability has a CVSS score of 9.0 out of 10, highlighting its severity. According to the U.S. Cybersecurity and Infrastructure Security Agency (CISA), this flaw affects Sitecore Experience Manager (XM), Experience Platform (XP), Experience Commerce (XC), and Managed Cloud, allowing for deserialization of untrusted data through default machine keys. This presents an opportunity for attackers to execute remote code by exploiting exposed ASP.NET machine keys. Mandiant, a Google-owned cybersecurity firm, reported that the ongoing ViewState deserialization attacks utilized a sample machine key found in Sitecore deployment guides from 2017 and earlier. The threat intelligence team…