Which products and versions are affected by CVE-2009-2521?

Affected: Internet Information Services (Microsoft). The full list is in the CVE brief.

Is CVE-2009-2521 being exploited in the wild?

It is exploited in the wild, listed in Industry KEV feed since Feb 14, 2023 and is known to be used in ransomware campaigns.

Is CVE-2009-2521 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Is there a public exploit for CVE-2009-2521?

Public exploit code is available.

Is there a fix for CVE-2009-2521?

Fixed versions are available, including Internet Information Services 7.0.

How urgently should CVE-2009-2521 be patched?

Brandefense priority: patch immediately, because it is listed as exploited in the wild.

Request A Demo

Vulnerability Intelligence

CVE-2009-2521

MediumExploitedPublic exploit

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,…

Published Sep 4, 2009 · Updated Apr 22, 2026

Key Facts

Patch immediately

CVE-2009-2521 is a medium-severity vulnerability (CVSS 5.0 v2) affecting Internet Information Services (Microsoft).
It is exploited in the wild, listed in Industry KEV feed since Feb 14, 2023 and is known to be used in ransomware campaigns. Public exploit code is available.
EPSS estimates a 82% probability of exploitation in the next 30 days.
Fixed versions are available, including Internet Information Services 7.0.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

CVSS v2

5.0

AV:N/AC:L/Au:N/C:N/I:N/A:P

EPSS (30-day exploit likelihood)

82%

Higher than 99.6% of all scored CVEs

Exploited in the wild

Yes

1 catalog listing, used by ransomware

Public exploit code

Available

Proof-of-concept or weaponized module

Get the full CVE-2009-2521 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

Description

Known-Exploited Catalog Listings

Catalog	Added	Remediation due	Ransomware use
Industry KEV feed	Feb 14, 2023	n/a	Known

Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Affected Products

1 affected entries in total

Product	Affected versions	Fixed in
Internet Information ServicesMicrosoft	See advisory	7.0

Patched Releases

Internet Information Services

7.0

Timeline

Publicly disclosed
Sep 4, 2009
Added to Industry KEV feed
Feb 14, 2023
Last updated
Apr 22, 2026

Weakness Type

CWE-400 Uncontrolled Resource Consumption

References

2 more references in the full CVE brief

FAQ

Common Questions.

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 ..
Affected: Internet Information Services (Microsoft). The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed since Feb 14, 2023 and is known to be used in ransomware campaigns.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Internet Information Services 7.0.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

Is CVE-2009-2521 Running On Your Attack Surface?

Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.