# CVE-2005-4840: Null dereference in n/a

> Remote attackers can crash Internet Explorer 6 by instantiating the Outlook Express Address Book COM object, causing a denial of service.

- **Severity:** Medium 4.3 (`AV:N/AC:M/Au:N/C:N/I:N/A:P`)
- **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:** 7 Jun 2007
- **Updated:** 8 Aug 2024
- **Also known as:** GHSA-gggx-f55h-83w3

## What is CVE-2005-4840?

CVE-2005-4840 is a medium-severity vulnerability in n/a, published on 7 Jun 2007. 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

The Outlook Express Address Book control, when using Internet Explorer 6, allows remote attackers to cause a denial of service (NULL dereference and browser crash) by creating the OutlookExpress.AddressBook COM object, which is not intended for use within Internet Explorer.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2005-4840?

It affects 1 product.


Products: Microsoft Outlook Express Book Control.

## How do I fix CVE-2005-4840?

No fix has been published for CVE-2005-4840 yet. Limit exposure of the affected software until one is available.

## Is CVE-2005-4840 being exploited?

There is no known exploitation of CVE-2005-4840 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2005-4840 and fix it if it is affected.

What it is: CVE-2005-4840 is a medium-severity vulnerability in n/a, published on 7 Jun 2007. 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-2005-4840 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-2005-4840/ (Markdown: https://insights.sbomify.com/CVE-2005-4840/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2005-4840
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2005-4840
- OSV: https://osv.dev/vulnerability/CVE-2005-4840

---
From sbomify Insights: https://insights.sbomify.com/CVE-2005-4840/
Summaries are generated and may contain mistakes; the official description above is the record.