# CVE-2002-0518: Null dereference in n/a

> Remote attackers can crash FreeBSD systems via SYN packets or socket restarts due to null pointer dereferences in the SYN cache mechanism.

- **Severity:** Medium 5.0 (`AV:N/AC:L/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:** Not needed
- **Fix available:** No
- **Published:** 11 Jun 2002
- **Updated:** 8 Aug 2024
- **Also known as:** GHSA-9x25-pv9q-883c

## What is CVE-2002-0518?

CVE-2002-0518 is a medium-severity vulnerability in Freebsd Freebsd, published on 11 Jun 2002. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The SYN cache (syncache) and SYN cookie (syncookie) mechanism in FreeBSD 4.5 and earlier allows remote attackers to cause a denial of service (crash) (1) via a SYN packet that is accepted using syncookies that causes a null pointer to be referenced for the socket's TCP options, or (2) by killing and restarting a process that listens on the same socket, which does not properly clear the old inpcb pointer on restart.

## Which versions are affected by CVE-2002-0518?

It affects 1 product.


Products: Freebsd Freebsd.

## How do I fix CVE-2002-0518?

No fix has been published for CVE-2002-0518 yet. Limit exposure of the affected software until one is available.

## Is CVE-2002-0518 being exploited?

There is no known exploitation of CVE-2002-0518 in the wild and no public exploit code.

## Other vulnerabilities in Freebsd Freebsd

- [CVE-2018-17160](https://insights.sbomify.com/CVE-2018-17160/): Memory corruption in FreeBSD (critical 10.0)
- [CVE-2014-3954](https://insights.sbomify.com/CVE-2014-3954/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-4304](https://insights.sbomify.com/CVE-2006-4304/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-0226](https://insights.sbomify.com/CVE-2006-0226/): Integer overflow in n/a (critical 10.0)
- [CVE-2004-0002](https://insights.sbomify.com/CVE-2004-0002/): Denial of service in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2002-0518 and fix it if it is affected.

What it is: CVE-2002-0518 is a medium-severity vulnerability in Freebsd Freebsd, published on 11 Jun 2002. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2002-0518 in the wild and no public exploit code.

Affected product: Freebsd Freebsd. 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-2002-0518/ (Markdown: https://insights.sbomify.com/CVE-2002-0518/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2002-0518
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2002-0518
- OSV: https://osv.dev/vulnerability/CVE-2002-0518

---
From sbomify Insights: https://insights.sbomify.com/CVE-2002-0518/
Summaries are generated and may contain mistakes; the official description above is the record.