NVD / CVE Program· CNA microsoft

CVE-2009-2521: Stack consumption vulnerability in the FTP Service in Microsoft Internet Information Services (IIS) 5.0 through 7.0 allows remote authentica

Noroxi assessment

Priority: Plan (action score 45/100)

A ready-made attack module is public (Metasploit); exploiting it takes no special expertise.
Public proof-of-concept code exists (Exploit-DB); there is no record of exploitation in the wild.
Probability of exploitation in the next 30 days: 82.2% (FIRST EPSS); higher than 99.6% of all records.
No special conditions are required; it is repeatable.
According to the record, no fixed version is available yet.

Add it to your regular patch cycle. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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."

MediumCVSS 5.0 · v2.0—Weaponized No fix recorded

BDU:2015-10407

Published: Sep 4, 2009
Updated: Jun 16, 2026
EPSS: 82.2% · 99th percentile
CWE: CWE-400

Report tools

JSON

Action score

Plan

Add it to your regular patch cycle.

CVSS: 20 / 40 · 5.0 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 25 / 30 · 82.2%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
Weaponized exploit exists
No fixed version yet

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
microsoft	internet information services	cpe:2.3:a:microsoft:internet_information_services

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

microsoft internet information services5.0 and later · up to 7.0 inclusive

Same product

microsoft: all records

Other highest-scoring records for the same primary product.

CVE-2017-7269Buffer overflow in the ScStoragePathFromUrl function in the WebDAV service in Internet Information Services (IIS) 6.0 in Microsoft Windows SKEV
99Now
CVE-2010-3972Heap-based buffer overflow in the TELNET_STREAM_CONTEXT::OnSendData function in ftpsvc.dll in Microsoft FTP Service 7.0 and 7.5 for Internet
68This week
CVE-2007-2815The "hit-highlighting" functionality in webhits.dll in Microsoft Internet Information Services (IIS) Web Server 5.0 only uses Windows NT ACL
62This week

Published before and after this one in the same product

← EarlierCVE-2009-1535Jun 10, 2009 · The WebDAV extension in Microsoft Internet Information Services (IIS) 5.1 and 6.0 allows remote attackers to bypass URI-based protection mec
59Plan
← EarlierCVE-2009-1122Jun 10, 2009 · The WebDAV extension in Microsoft Internet Information Services (IIS) 5.0 on Windows 2000 SP4 does not properly decode URLs, which allows re
60This week
Later →CVE-2009-4444Dec 29, 2009 · Microsoft Internet Information Services (IIS) 5.x and 6.x uses only the portion of a filename before a ; (semicolon) character to determine
43Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Evidence

Metasploit module ×1
Exploit-DB entry ×2

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
Source	Kind	Date
Metasploit module	auxiliary/dos/windows/ftp/iis_list_exhaustionMicrosoft IIS FTP Server LIST Stack Exhaustionauxiliary	2009-09-03
Exploit-DB entry	dos	2009-09-04
Exploit-DB entry	dos	2011-07-03

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

MetasploitSep 3, 2009-1 d
First PoCSep 4, 2009same day
PublishedSep 4, 2009
TodayNov 5, 2026+6271 d

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: P · the service can be disrupted

Attack complexity: Low
Confidentiality impact: None
Integrity impact: None
Availability impact: P

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

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

nvd-primary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Endpoint Denial of ServiceT1499

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

archives.neohapsis.com/archives/fulldisclosure/2009-09/0040.html

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records