# CVE-2011-1271: Code injection in n/a

> Attackers can execute arbitrary code by exploiting a JIT compiler flaw in .NET Framework when optimization is enabled, bypassing access restrictions via crafted applications.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 May 2011
- **Updated:** 17 Oct 2024
- **Also known as:** GHSA-w649-2qr9-fg6v

## What is CVE-2011-1271?

CVE-2011-1271 is a high-severity code injection vulnerability in Microsoft .Net Framework, published on 10 May 2011. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The JIT compiler in Microsoft .NET Framework 3.5 Gold and SP1, 3.5.1, and 4.0, when IsJITOptimizerDisabled is false, does not properly handle expressions related to null strings, which allows context-dependent attackers to bypass intended access restrictions, and consequently execute arbitrary code, in opportunistic circumstances by leveraging a crafted application, as demonstrated by (1) a crafted XAML browser application (aka XBAP), (2) a crafted ASP.NET application, or (3) a crafted .NET Framework application, aka ".NET Framework JIT Optimization Vulnerability."

Weakness: CWE-264, CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2011-1271?

It affects 1 product.


Products: Microsoft .Net Framework.

## How do I fix CVE-2011-1271?

No fix has been published for CVE-2011-1271 yet. Limit exposure of the affected software until one is available.

## Is CVE-2011-1271 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2011-1271 exists.

Public exploit code:

- Microsoft .NET Framework JIT Compiler - Optimization NULL String Remote Code Execution (exploitdb)

## 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-2011-1271 and fix it if it is affected.

What it is: CVE-2011-1271 is a high-severity code injection vulnerability in Microsoft .Net Framework, published on 10 May 2011. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2011-1271 exists.

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-2011-1271/ (Markdown: https://insights.sbomify.com/CVE-2011-1271/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-1271
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-1271
- OSV: https://osv.dev/vulnerability/CVE-2011-1271

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-1271/
Summaries are generated and may contain mistakes; the official description above is the record.