# CVE-2011-4622: Null dereference in n/a

> Local users can cause a denial of service via NULL pointer dereference in KVM PIT timer handling when irqchip is unavailable.

- **Severity:** Medium 4.9 (`AV:L/AC:L/Au:N/C:N/I:N/A:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Jan 2012
- **Updated:** 7 Aug 2024
- **Also known as:** GHSA-gqh3-j9ff-5g88

## What is CVE-2011-4622?

CVE-2011-4622 is a medium-severity vulnerability in n/a, published on 27 Jan 2012. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The create_pit_timer function in arch/x86/kvm/i8254.c in KVM 83, and possibly other versions, does not properly handle when Programmable Interval Timer (PIT) interrupt requests (IRQs) when a virtual interrupt controller (irqchip) is not available, which allows local users to cause a denial of service (NULL pointer dereference) by starting a timer.

## Which versions are affected by CVE-2011-4622?

It affects 1 product.


Products: Redhat Kvm.

## How do I fix CVE-2011-4622?

Apply the vendor's patch.

## Is CVE-2011-4622 being exploited?

There is no known exploitation of CVE-2011-4622 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2011-4622 and fix it if it is affected.

What it is: CVE-2011-4622 is a medium-severity vulnerability in n/a, published on 27 Jan 2012. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2011-4622 in the wild and no public exploit code.

Affected product: n/a. 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-2011-4622/ (Markdown: https://insights.sbomify.com/CVE-2011-4622/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-4622
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-4622
- OSV: https://osv.dev/vulnerability/CVE-2011-4622

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-4622/
Summaries are generated and may contain mistakes; the official description above is the record.