Over 511,000 End-of-Life IIS Instances Exposed, Heightening Security Risks

• •Over 511,000 End-of-Life IIS instances are currently exposed online.
• •These outdated servers no longer receive security updates from Microsoft.
• •Organizations are urged to secure their systems to mitigate potential threats.

Security researchers from The Shadowserver Foundation have discovered over 511,000 End-of-Life (EOL) Microsoft Internet Information Services (IIS) instances actively connected to the internet as of March 23, 2026. These outdated servers no longer receive security updates from Microsoft, posing a significant risk to organizations worldwide. The widespread exposure of these EOL systems creates a large attack surface that could be exploited by malicious actors. Organizations using these servers are urged to secure their systems promptly to mitigate potential threats. The situation highlights the importance of maintaining updated software to protect against vulnerabilities. The lack of standard security patches for these servers increases the likelihood of successful cyberattacks. As of now, no specific attack methods or exploitation cases have been reported, but the risk remains high due to the sheer number of vulnerable instances. This discovery emphasizes the ongoing challenge of managing legacy systems in cybersecurity.