# CVE-2006-1993: Use after free in n/a

> Remote attackers can cause denial of service or execute arbitrary code in Firefox via crafted JavaScript exploiting a use-after-free in designMode.

- **Severity:** Medium 5.1 (`AV:N/AC:H/Au:N/C:P/I:P/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:** Yes
- **Published:** 25 Apr 2006
- **Updated:** 7 Aug 2024
- **Also known as:** DSA-1053-1, DSA-1055-1, GHSA-gh5c-2j93-h8q7

## What is CVE-2006-1993?

CVE-2006-1993 is a medium-severity use after free vulnerability in Mozilla Firefox, published on 25 Apr 2006. 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

Mozilla Firefox 1.5.0.2, when designMode is enabled, allows remote attackers to cause a denial of service and possibly execute arbitrary code via certain Javascript that is not properly handled by the contentWindow.focus method in an iframe, which causes a reference to a deleted controller context object.  NOTE: this was originally claimed to be a buffer overflow in (1) js320.dll and (2) xpcom_core.dll, but the vendor disputes this claim.

Weakness: CWE-399

## Which versions are affected by CVE-2006-1993?

It affects 1 product.


Products: Mozilla Firefox.

## How do I fix CVE-2006-1993?

Upgrade to a fixed version.

## Is CVE-2006-1993 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2006-1993 exists.

Public exploit code:

- Mozilla Firefox 1.5.0.2 - 'js320.dll/xpcom_core.dll' Denial of Service (PoC) (exploitdb)

## Other vulnerabilities in Mozilla Firefox

- [CVE-2019-11708](https://insights.sbomify.com/CVE-2019-11708/): Mozilla Firefox and Thunderbird Sandbox Escape (critical 10.0, exploited in the wild)
- [CVE-2010-3765](https://insights.sbomify.com/CVE-2010-3765/): Mozilla Multiple Products Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2022-26486](https://insights.sbomify.com/CVE-2022-26486/): Mozilla Firefox Use-After-Free (critical 9.6, exploited in the wild)
- [CVE-2022-26485](https://insights.sbomify.com/CVE-2022-26485/): Mozilla Firefox Use-After-Free (high 8.8, exploited in the wild)
- [CVE-2019-11707](https://insights.sbomify.com/CVE-2019-11707/): Mozilla Firefox and Thunderbird Type Confusion (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2006-1993 and fix it if it is affected.

What it is: CVE-2006-1993 is a medium-severity use after free vulnerability in Mozilla Firefox, published on 25 Apr 2006. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2006-1993 exists.

Affected product: Mozilla Firefox. 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-2006-1993/ (Markdown: https://insights.sbomify.com/CVE-2006-1993/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2006-1993
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2006-1993
- OSV: https://osv.dev/vulnerability/CVE-2006-1993

---
From sbomify Insights: https://insights.sbomify.com/CVE-2006-1993/
Summaries are generated and may contain mistakes; the official description above is the record.