CVE-2009-2521

Exp

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."

Published: 2009-09-04 Last update: 2026-04-23 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2009-2521 is rated High Exploit Risk (70/100): CVSS Medium severity, with high exploitation likelihood (EPSS 60.77%, 98th percentile). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2009-2521

EDB-ID Source Kind Published Link
17476 exploit_db edb 2011-07-03 Exploit-DB ↗
9587 exploit_db edb 2009-09-04 Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2009-2521

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-04 60.13% 60.77% +0.65%
2 2026-03-01 60.77% 60.13% -0.65%
3 2026-02-04 — 60.77% —

Full EPSS history (48 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2009-2521

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2009-2521

Affected software / configurations for CVE-2009-2521

Vendor Product Version Raw CPE
microsoft internet_information_services >= 5.0, <= 7.0 cpe:2.3:a:microsoft:internet_information_services:*:*:*:*:*:*:*:*

References for CVE-2009-2521

cvelogic Threat Intelligence