# CVE-2009-0091: Code injection in n/a

> Remote attackers can execute arbitrary code via crafted applications due to improper type verification in Microsoft .NET Framework.

- **Severity:** Critical 9.3 (`AV:N/AC:M/Au:N/C:C/I:C/A:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 14 Oct 2009
- **Updated:** 7 Aug 2024
- **Also known as:** GHSA-ccxf-7q2f-693x

## What is CVE-2009-0091?

CVE-2009-0091 is a critical code injection vulnerability in Microsoft .Net Framework, published on 14 Oct 2009. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Microsoft .NET Framework 2.0, 2.0 SP1, and 3.5 does not properly enforce a certain type-equality constraint in .NET verifiable code, which allows remote attackers to execute arbitrary code via (1) a crafted XAML browser application (XBAP), (2) a crafted ASP.NET application, or (3) a crafted .NET Framework application, aka "Microsoft .NET Framework Type Verification Vulnerability."

Weakness: CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2009-0091?

It affects 7 products.


Products: Microsoft .Net Framework, Microsoft Windows 2000, Microsoft Windows 7, Microsoft Windows Server 2003, Microsoft Windows Server 2008, Microsoft Windows Vista, Microsoft Windows Xp.

## How do I fix CVE-2009-0091?

No fix has been published for CVE-2009-0091 yet. Limit exposure of the affected software until one is available.

## Is CVE-2009-0091 being exploited?

There is no known exploitation of CVE-2009-0091 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft .Net Framework

- [CVE-2020-0646](https://insights.sbomify.com/CVE-2020-0646/): Microsoft .NET Framework Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2017-8759](https://insights.sbomify.com/CVE-2017-8759/): Microsoft .NET Framework Remote Code Execution (high 7.8, exploited in the wild)
- [CVE-2015-1671](https://insights.sbomify.com/CVE-2015-1671/): Microsoft Windows Remote Code Execution (high 7.8, exploited in the wild)
- [CVE-2024-29059](https://insights.sbomify.com/CVE-2024-29059/): Microsoft .NET Framework Information Disclosure (high 7.5, exploited in the wild)
- [CVE-2014-4073](https://insights.sbomify.com/CVE-2014-4073/): Privilege escalation in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2009-0091 and fix it if it is affected.

What it is: CVE-2009-0091 is a critical code injection vulnerability in Microsoft .Net Framework, published on 14 Oct 2009. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2009-0091 in the wild and no public exploit code.

Affected product: Microsoft .Net Framework. 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-2009-0091/ (Markdown: https://insights.sbomify.com/CVE-2009-0091/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2009-0091
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2009-0091
- OSV: https://osv.dev/vulnerability/CVE-2009-0091

---
From sbomify Insights: https://insights.sbomify.com/CVE-2009-0091/
Summaries are generated and may contain mistakes; the official description above is the record.