# CVE-2009-2521: Denial of service in n/a

> Remote authenticated users can crash the IIS FTP service via a crafted list command, causing denial of service.

- **Severity:** Medium 5.0 (`AV:N/AC:L/Au:N/C:N/I:N/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Sep 2009
- **Updated:** 7 Aug 2024
- **Also known as:** GHSA-w8g4-h8cc-352m

## What is CVE-2009-2521?

CVE-2009-2521 is a medium-severity denial of service vulnerability in Microsoft Internet Information Services, published on 4 Sep 2009. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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."

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2009-2521?

It affects 1 product.


Products: Microsoft Internet Information Services.

## How do I fix CVE-2009-2521?

No fix has been published for CVE-2009-2521 yet. Limit exposure of the affected software until one is available.

## Is CVE-2009-2521 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2009-2521 exists.

Public exploit code:

- Microsoft IIS FTP Server LIST Stack Exhaustion (metasploit)
- Microsoft IIS 5.0/6.0 FTP Server - Stack Exhaustion Denial of Service (exploitdb)
- Microsoft IIS 7.0 FTP Server - Stack Exhaustion Denial of Service (MS09-053) (Metasploit) (exploitdb)

## Other vulnerabilities in Microsoft Internet Information Services

- [CVE-2017-7269](https://insights.sbomify.com/CVE-2017-7269/): Microsoft Windows Server Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2010-3972](https://insights.sbomify.com/CVE-2010-3972/): Memory corruption in n/a (critical 10.0)
- [CVE-2008-4301](https://insights.sbomify.com/CVE-2008-4301/): Other in n/a (critical 10.0)
- [CVE-2007-2815](https://insights.sbomify.com/CVE-2007-2815/): The "hit-highlighting" functionality in webhits.dll in Microsoft Internet Information Services (IIS) Web Server 5.0 only uses Windows NT ACL (critical 10.0)
- [CVE-2003-0224](https://insights.sbomify.com/CVE-2003-0224/): Buffer overflow in ssinc.dll for Microsoft Internet Information Services (IIS) 5.0 allows local users to execute arbitrary code via a web pa (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2009-2521 and fix it if it is affected.

What it is: CVE-2009-2521 is a medium-severity denial of service vulnerability in Microsoft Internet Information Services, published on 4 Sep 2009. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2009-2521 exists.

Affected product: Microsoft Internet Information Services. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2009-2521/ (Markdown: https://insights.sbomify.com/CVE-2009-2521/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2009-2521
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2009-2521
- OSV: https://osv.dev/vulnerability/CVE-2009-2521

---
From sbomify Insights: https://insights.sbomify.com/CVE-2009-2521/
Summaries are generated and may contain mistakes; the official description above is the record.