CVE-2009-2521: Microsoft Internet Information Services

Medium severity, CVSS 5.0. EPSS: 82.3% chance of exploitation in the next 30 days.

Stack consumption vulnerability in the FTP Service in Microsoft Internet Information Services (IIS) 5.0 through 7.0 allows remote authenticated users to cause a denial of service (daemon crash) via a list (ls) -R command containing a wildcard that references a subdirectory, followed by a .. (dot dot), aka "IIS FTP Service DoS Vulnerability."

Affected products

• Microsoft Internet Information Services: from 5.0, up to and including 7.0

Published 2009-09-04. Last modified 2026-06-16.